An exact algorithm of relationship of handle steering angle and contact displacement of depressurized pilot valve was proposed. As compared with the method for approximately calculating the displacement of the contact with the linear formula at present, it was found that, in the small angle range, the actual displacement of the contact was basically equal to the linear calculation, but after the angle become larger, and the error was bigger and bigger. The threedimensional (3D) model of pilot valve was established with SolidWorks, and the correctness of the exact algorithm was verified by simulations. In order to improve the fine tuning control performance of the depressurized pilot valve, by optimized the structure of platen of pilot valve, the error caused by handle steering angle becoming large is compensated, and the linear range of use of the handle steering angle is increased.