diff --git a/nnvm/python/nnvm/frontend/onnx.py b/nnvm/python/nnvm/frontend/onnx.py
index bd5a0f4df1c7..129c5089caee 100644
--- a/nnvm/python/nnvm/frontend/onnx.py
+++ b/nnvm/python/nnvm/frontend/onnx.py
@@ -186,6 +186,7 @@ def _impl_v1(cls, inputs, attr, params):
             inputs[0] = _sym.transpose(inputs[0], axes=(1, 0))
         if not transB:
             inputs[1] = _sym.transpose(inputs[1], axes=(1, 0))
+        inputs[0] = _sym.flatten(inputs[0])
         return _sym.dense(
             alpha * inputs[0], inputs[1], beta * inputs[2], units=channels)