The drifter drill hydraulic control system needs to adjust the pressure parameters automatically under thrust and rotation conditions to match the pressure and flow between multiactuators, achieving efficient drilling performance and avoiding free hammering.According to the percussion pressure control principle of this hydraulic drifter, a nolinear mathematic model, which arguments were identified by the experimental data, was set up for this hydraulic control system.This mathematic model illustrated by block diagram method was used to investigate the dynamic performance of the percussion pressure pilot control system. The laws that structural and fluid flowing parameters affected the working performance of this hydraulic system were obtained, providing reference for drill rig product development.