The walk speed limiting brake circuit was identified to use based on the working conditions of the mine crawler car. The mathematical model of the walking speed limiting system was adopted by using the power bond graph when the crawler car walked, and the hydraulic circuit state equations were obtained. The system simulation model was built by using AMESim. The influences of the pre-stressing force, spring stiffness and damping hole diameter of back pressure valve on hydraulic braking characteristics of motor were analyzed. The results show that the characteristics of the hydraulic motor braking are affected by the damping hole diameter most, the second one is the spring stiffness, the last one is the pre-stressing force.