Abstract: An experimental research on river bed deformation near piers is reported in this paper.The flow structure and river bed deformation near piers when an angle exists between the trend of piers and the direction of main-flow will be different from those when the angle equal to zero,such as the flow-obstructing width will increase,the diversion function will occur,the partial scouring pits get larger and deeper,and the main-flow and thalweg within a certain distance downstream the piers will deviate to one side.