diff --git a/python/tvm/relay/frontend/onnx.py b/python/tvm/relay/frontend/onnx.py
index a29bf59c653ae..9bfa560a778f7 100644
--- a/python/tvm/relay/frontend/onnx.py
+++ b/python/tvm/relay/frontend/onnx.py
@@ -2210,6 +2210,10 @@ class GRU(RNN):
     def generate_gru(
         cls, X_steps, H_t, W, R, B, linear_before_reset, f_act, g_act, W_dtype, backwards=False
     ):
+        """Create an unrolled gru loop.
+
+        See https://github.com/onnx/onnx/blob/master/docs/Operators.md for math.
+        """
         h_list = []
         seq_length = len(X_steps)
         for i in range(seq_length):