diff --git a/lmdeploy/pytorch/backends/dlinfer/ascend/op_backend.py b/lmdeploy/pytorch/backends/dlinfer/ascend/op_backend.py
index b7ce2a6846..e48ab79f18 100644
--- a/lmdeploy/pytorch/backends/dlinfer/ascend/op_backend.py
+++ b/lmdeploy/pytorch/backends/dlinfer/ascend/op_backend.py
@@ -148,14 +148,27 @@ def get_total_slots():
             return cls.total_slots
 
         def get_cpu_seqlens(is_decoding, is_unpaged_prefill):
+            """Get sequence lengths on CPU.
+
+            Returns:
+                q_seqlens_cpu: query sequence lengths (per sequence).
+                kv_seqlens_cpu: kv sequence lengths (per sequence), used for
+                    list/max seqlens calculation.
+                kv_seqlens_expanded: kv sequence lengths expanded per token via
+                    repeat_interleave, used for attention metadata.
+            """
             if is_decoding:
-                q_seqlens_cpu, kv_seqlens_cpu = None, step_context.kv_seqlens.cpu()
+                q_seqlens_cpu = None
+                kv_seqlens_cpu = kv_seqlens_expanded = step_context.kv_seqlens.cpu()
             elif is_unpaged_prefill:
-                q_seqlens_cpu = kv_seqlens_cpu = step_context.q_seqlens.cpu()
+                q_seqlens_cpu = step_context.q_seqlens.cpu()
+                kv_seqlens_cpu = kv_seqlens_expanded = q_seqlens_cpu
             else:
                 q_seqlens_cpu = step_context.q_seqlens.cpu()
                 kv_seqlens_cpu = step_context.kv_seqlens.cpu()
-            return q_seqlens_cpu, kv_seqlens_cpu
+                # Expand kv_seqlens to per-token for paged prefill attention
+                kv_seqlens_expanded = kv_seqlens_cpu.repeat_interleave(q_seqlens_cpu, 0)
+            return q_seqlens_cpu, kv_seqlens_cpu, kv_seqlens_expanded
 
         def get_list_seqlens(is_decoding, is_unpaged_prefill, q_seqlens_cpu=None, kv_seqlens_cpu=None):
             if is_decoding:
@@ -219,7 +232,8 @@ def get_kv_start_indices_and_attention_mask(is_decoding, is_unpaged_prefill, q_s
 
             return kv_start_indices, attention_mask
 
-        q_seqlens_cpu, kv_seqlens_cpu = get_cpu_seqlens(step_context.is_decoding, is_unpaged_prefill)
+        q_seqlens_cpu, kv_seqlens_cpu, kv_seqlens_expanded = get_cpu_seqlens(step_context.is_decoding,
+                                                                             is_unpaged_prefill)
         q_seqlens_list, kv_seqlens_list = get_list_seqlens(step_context.is_decoding, is_unpaged_prefill, q_seqlens_cpu,
                                                            kv_seqlens_cpu)
         max_q_seq_len, max_kv_seq_len = get_max_seqlens(step_context.is_decoding, is_unpaged_prefill, q_seqlens_list,
@@ -248,7 +262,9 @@ def get_kv_start_indices_and_attention_mask(is_decoding, is_unpaged_prefill, q_s
             step_context.block_offsets,
             q_start_loc=None,
             q_seqlens=q_seqlens_cpu,
-            kv_seqlens=kv_seqlens_cpu,
+            # kv_seqlens_expanded is only expanded in paged prefill,
+            # otherwise it equals kv_seqlens_cpu
+            kv_seqlens=kv_seqlens_expanded,
             kv_start_indices=kv_start_indices,
             block_size=block_size,
             attention_mask=attention_mask,