Thank you so much for you answer, I solved this by disconnecting the input mesh for RetargetPoseFromMesh node, and make sure the UseAttachedParent option is checked.
Pretty strange in my case, I use the same blueprint for my player character and ai character, my player character has retargeted animations but the ai character has no retargeted animation at all(Keep the init pose all the time).
Maybe there is someting wrong with the RetargetPoseFromMesh node, in some cases it will ignore the input mesh, so just give no input mesh to avoid this.
Edit: for anyone met this problem, note that just set the input mesh to null will not avoid this problem, you should DISCONNECT the input mesh.