The paper aims to analyze the fluid field of different valve core structure based on the direct influences of spool valve structure on fluid field of spool valve, so as to improve spool valve performance. U-shaped, triangular and throttling groove-free valve core structures were adopted and the fluid-structure interaction module of ADINA was applied to analyze and calculate the spool valve fluid field and research the fluid speed and pressure distribution condition in the valve channel. The flow rate was high at the valve port. The speed of throttling groove-free valve core decreased the most at the valve port and that of the U-shaped throttling groove valve core decreased the least. The pressure change of U-shaped throttling groove valve core was small in the entire channel, and the pressure change of throttling groove free valve core was the largest. The valve spool with throttling groove could significantly improve fluid field distribution in the valve channel and the performance of valve, in which the U-shaped throttling groove has good performance.