diff --git a/dnn/src/common/utils.h b/dnn/src/common/utils.h
index d688166c..a12f2a53 100644
--- a/dnn/src/common/utils.h
+++ b/dnn/src/common/utils.h
@@ -41,6 +41,7 @@
 #endif
 
 #define rep(i, n) for (auto i = decltype(n){0}; i < (n); ++i)
+#define rep_step(i, n, step) for (auto i = decltype(n){0}; i < (n); i += (step))
 
 #define megdnn_assert_contiguous(layout)                              \
     do {                                                              \
diff --git a/dnn/src/fallback/conv_bias/opr_impl.cpp b/dnn/src/fallback/conv_bias/opr_impl.cpp
index c4e5a7ac..4619941d 100644
--- a/dnn/src/fallback/conv_bias/opr_impl.cpp
+++ b/dnn/src/fallback/conv_bias/opr_impl.cpp
@@ -375,6 +375,25 @@ const T* ConvBiasImpl::NCBKernParam::filter(size_t group_pack_id,
 
             break;
         }
+        case Param::Format::NCHW44: {
+            size_t group = filter_meta.group;
+            size_t icpg = filter_meta.icpg;
+            size_t ocpg = filter_meta.ocpg;
+            //! four format of weight layout
+            //! 1. {oc/4, ic/4, fh, fw, 4, 4},
+            //! 2. {g, oc/4, ic/4, fh, fw, 4, 4},
+            //! 3. {g/4, fh, fw, 1, 1, 4}, 4. {oc/4, fh, fw, ic, 4}
+            megdnn_assert((icpg % 4 == 0 && ocpg % 4 == 0) ||
+                                  (group % 4 == 0 && icpg == 1 && ocpg == 1 &&
+                                   pack_group_size > 1) ||
+                                  (group == 1 && ocpg % 4 == 0),
+                          "The filter shepe is not right of nchw44");
+            group_offset = pack_group_size * group_pack_id * filter_meta.icpg *
+                           filter_meta.ocpg * filter_meta.spatial[0] *
+                           filter_meta.spatial[1] * filter_type.size();
+
+            break;
+        }
         case ConvBiasImpl::Param::Format::NCHW_WINOGRAD:
         case ConvBiasImpl::Param::Format::NCHW88_WINOGRAD: {
             //! four format of weight layout