diff --git a/tests/ut/_310p/ops/test_mm_encoder_attention_310.py b/tests/ut/_310p/ops/test_mm_encoder_attention_310.py
new file mode 100644
index 00000000..213dcdfa
--- /dev/null
+++ b/tests/ut/_310p/ops/test_mm_encoder_attention_310.py
@@ -0,0 +1,81 @@
+#
+# Copyright (c) 2026 Huawei Technologies Co., Ltd. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from unittest import mock
+
+import torch
+
+from vllm_ascend import utils
+from vllm_ascend._310p.ops.mm_encoder_attention import AscendMMEncoderAttention310
+
+
+def test_register_customop_overrides_mm_encoder_attention_for_310p():
+    original_registered = utils._ASCEND_CUSTOMOP_IS_REIGISTERED
+    try:
+        utils._ASCEND_CUSTOMOP_IS_REIGISTERED = False
+        with (
+            mock.patch("vllm.model_executor.custom_op.CustomOp.register_oot"),
+            mock.patch("vllm_ascend.utils.is_310p", return_value=True),
+        ):
+            utils.register_ascend_customop()
+
+        assert utils.REGISTERED_ASCEND_OPS["MMEncoderAttention"] is AscendMMEncoderAttention310
+    finally:
+        utils._ASCEND_CUSTOMOP_IS_REIGISTERED = original_registered
+
+
+def test_mm_encoder_attention_310_forward_oot_with_padding():
+    layer = AscendMMEncoderAttention310.__new__(AscendMMEncoderAttention310)
+    layer.num_heads = 4
+    layer.num_kv_heads = 2
+    layer.head_size = 80
+    layer.enable_pad = True
+    layer.scale_value = layer.head_size**-0.5
+
+    bsz, q_len, kv_len = 2, 3, 3
+    query = torch.randn(bsz, q_len, layer.num_heads, layer.head_size)
+    key = torch.randn(bsz, kv_len, layer.num_kv_heads, layer.head_size)
+    value = torch.randn(bsz, kv_len, layer.num_kv_heads, layer.head_size)
+
+    capture = {}
+
+    def fake_flash_attention_unpad(*, query, key, value, seq_len, scale_value, num_heads, num_kv_heads, out):
+        capture["query_shape"] = query.shape
+        capture["key_shape"] = key.shape
+        capture["value_shape"] = value.shape
+        capture["seq_len"] = seq_len
+        capture["scale_value"] = scale_value
+        capture["num_heads"] = num_heads
+        capture["num_kv_heads"] = num_kv_heads
+        out.copy_(query + 1.0)
+
+    with mock.patch(
+        "vllm_ascend._310p.ops.mm_encoder_attention.torch_npu._npu_flash_attention_unpad",
+        side_effect=fake_flash_attention_unpad,
+        create=True,
+    ):
+        out = layer.forward_oot(query, key, value)
+
+    assert capture["query_shape"] == (bsz * q_len, layer.num_heads, 128)
+    assert capture["key_shape"] == (bsz * kv_len, layer.num_heads, 128)
+    assert capture["value_shape"] == (bsz * kv_len, layer.num_heads, 128)
+    assert capture["seq_len"].device.type == "cpu"
+    torch.testing.assert_close(capture["seq_len"], torch.tensor([q_len, q_len], dtype=torch.int32))
+    assert capture["num_heads"] == layer.num_heads
+    assert capture["num_kv_heads"] == layer.num_kv_heads
+
+    assert out.shape == query.shape
+    torch.testing.assert_close(out, query + 1.0)
+
diff --git a/vllm_ascend/_310p/ops/mm_encoder_attention.py b/vllm_ascend/_310p/ops/mm_encoder_attention.py
new file mode 100644
index 00000000..62504375
--- /dev/null
+++ b/vllm_ascend/_310p/ops/mm_encoder_attention.py
@@ -0,0 +1,142 @@
+#
+# Copyright (c) 2025 Huawei Technologies Co., Ltd. All Rights Reserved.
+# This file is a part of the vllm-ascend project.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import einops
+import torch
+import torch.nn.functional as F
+import torch_npu
+from vllm.model_executor.layers.attention.mm_encoder_attention import MMEncoderAttention  # type: ignore
+
+MIN_PAD_SIZE: int = 64  # min_size to pad weight
+MAX_PAD_SIZE: int = 128  # max_size to pad weight
+
+# Use seq_lens CPU cache to avoid frequent d2h copy.
+# AscendMMEncoderAttention310 will copy the cu_seqlens from NPU to CPU in every
+# forward, since the op _npu_flash_attention_unpad() requires CPU cu_seqlens
+# (otherwise it will break down).
+# Thus, we use seq_lens_cpu_cache to cache this tensor, since it's shared
+# between all layers, but may change in different forward step. When the
+# current layer_index is 0, we update the cache, otherwise we directly use the
+# cache to avoid frequent diff and copy operations, which are costful.
+seq_lens_cpu_cache: torch.Tensor = None
+
+
+class AscendMMEncoderAttention310(MMEncoderAttention):
+    def __init__(
+        self,
+        num_heads: int,
+        head_size: int,
+        scale: float | None = None,
+        num_kv_heads: int | None = None,
+        prefix: str = "",
+    ) -> None:
+        """
+        Args:
+            num_heads: number of attention heads per partition.
+            head_size: hidden_size per attention head.
+            scale: scale factor.
+            num_kv_heads: number of kv heads.
+            prefix: This has no effect, it is only here to make it easier to
+                    swap between Attention and MMEncoderAttention.
+            multimodal_config: configs for multi-modal.
+        """
+        super().__init__(
+            num_heads=num_heads,
+            head_size=head_size,
+            scale=scale,
+            num_kv_heads=num_kv_heads,
+            prefix=prefix,
+        )
+
+        self.enable_pad = self.head_size > MIN_PAD_SIZE and self.head_size < MAX_PAD_SIZE
+        self.scale_value = self.head_size**-0.5
+
+    def _reshape_qkv_to_3d(
+        self,
+        query: torch.Tensor,
+        key: torch.Tensor,
+        value: torch.Tensor,
+        bsz: int,
+        q_len: int,
+        kv_len: int,
+    ) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
+        """
+        Reshape query, key, value to 3D tensors:
+        (batch_size * seq_len, num_heads, head_size)
+        """
+        query = query.view(bsz * q_len, self.num_heads, self.head_size)
+        key = key.view(bsz * kv_len, self.num_kv_heads, self.head_size)
+        value = value.view(bsz * kv_len, self.num_kv_heads, self.head_size)
+        self.num_queries_per_kv = self.num_heads // self.num_kv_heads
+        if (num_repeat := self.num_queries_per_kv) > 1:
+            # Handle MQA and GQA
+            key = torch.repeat_interleave(key, num_repeat, dim=1)
+            value = torch.repeat_interleave(value, num_repeat, dim=1)
+
+        return query, key, value
+
+    def forward_oot(
+        self,
+        query: torch.Tensor,
+        key: torch.Tensor,
+        value: torch.Tensor,
+        cu_seqlens: torch.Tensor | None = None,
+        max_seqlen: torch.Tensor | None = None,  # Only used for Flash Attention
+        sequence_lengths: torch.Tensor | None = None,
+    ):
+        bsz, q_len = query.size()[:2]
+        kv_len = key.size(1)
+        is_reshaped = query.dim() == 4
+
+        # Directly use seq_lens cpu cache to avoid d2h copy.
+        if cu_seqlens is None:
+            cu_seqlens = torch.arange(0, (bsz + 1) * q_len, step=q_len, dtype=torch.int32, device="cpu")
+        seq_lens_cpu = torch.diff(cu_seqlens).to("cpu")
+
+        # q, k, v: [b, s, head, head_dim] -> [b * s, head, head_dim]
+        q, k, v = self._reshape_qkv_to_3d(query, key, value, bsz, q_len, kv_len)
+
+        if self.enable_pad:
+            origin_shape = q.shape[-1]
+            pad_len = MAX_PAD_SIZE - origin_shape
+            # [b * s, head, head_dim] -> [b * s, head, MAX_PAD_SIZE]
+            q = F.pad(q, (0, pad_len), mode="constant", value=0)
+            k = F.pad(k, (0, pad_len), mode="constant", value=0)
+            v = F.pad(v, (0, pad_len), mode="constant", value=0)
+
+        context_layer = torch.empty_like(q)
+
+        # operator requires pta version >= 2.5.1
+        torch_npu._npu_flash_attention_unpad(
+            query=q,
+            key=k,
+            value=v,
+            seq_len=seq_lens_cpu,
+            scale_value=self.scale_value,
+            num_heads=self.num_heads,
+            num_kv_heads=self.num_kv_heads,
+            out=context_layer,
+        )
+
+        if self.enable_pad:
+            context_layer = context_layer[..., :origin_shape]
+
+        if is_reshaped:
+            context_layer = einops.rearrange(context_layer, "(b s) h d -> b s h d", b=bsz).contiguous()
+        else:
+            context_layer = einops.rearrange(context_layer, "(b s) h d -> b s (h d)", b=bsz).contiguous()
+        return context_layer
diff --git a/vllm_ascend/utils.py b/vllm_ascend/utils.py
index 0f310e36..841e8562 100644
--- a/vllm_ascend/utils.py
+++ b/vllm_ascend/utils.py
@@ -662,6 +662,7 @@ def register_ascend_customop(vllm_config: VllmConfig | None = None):
         from vllm_ascend._310p.fused_moe.fused_moe import AscendFusedMoE310, AscendSharedFusedMoE310
         from vllm_ascend._310p.ops.activation import AscendSiluAndMul310
         from vllm_ascend._310p.ops.layernorm import AscendGemmaRMSNorm310, AscendRMSNorm310
+        from vllm_ascend._310p.ops.mm_encoder_attention import AscendMMEncoderAttention310
         from vllm_ascend._310p.ops.rotary_embedding import AscendRotaryEmbedding310
         from vllm_ascend._310p.ops.vocab_parallel_embedding import (
             AscendParallelLMHead310,
@@ -678,6 +679,7 @@ def register_ascend_customop(vllm_config: VllmConfig | None = None):
                 "SharedFusedMoE": AscendSharedFusedMoE310,
                 "ParallelLMHead": AscendParallelLMHead310,
                 "VocabParallelEmbedding": AscendVocabParallelEmbedding310,
+                "MMEncoderAttention": AscendMMEncoderAttention310,
             }
         )