Based on the Workbench platform, the fluid motion in the reversing valve under different boundary conditions was simulated and analyzed by twoway fluidstructure coupling. The variation law of the fluid characteristics of the hydraulic oil in the valve was obtained under the different opening degree and the flow rate, and the reason of the difference was analyzed. For the case of small opening degree, the gap flow of hydraulic oil was simulated separately, and the flow velocity and pressure distribution of the fluid flow were compared and analyzed. When the gap flows, the fluid movement was not uniform; hydraulic erosion analysis of the hydraulic system was carried out, and the erosion law of the valve was obtained. The stress distribution of the hydraulic system under the influence of the hydraulic oil was analyzed. The pressure distribution of the directional control valve in the hydraulic oil flow was obtained, and further, under the action of the position changes were analyzed.