Abstract:The structure and working principle of the double damper system for hydraulic rock drill were analyzed, its process was divided in three stages. Firstly, the system was in equilibrium. The position of the damping piston and the pressure of the chamber could be got through the force equilibrium equation; Then the mathematical model of the damping pistons deceleration process was built. Last is the return process of the damping piston. Afterwards, the mathematical model of each stage was calculated by the ode45 in the MATLAB. The damping pistons displacementtime curve and speedtime curve, the pressure curve of the first class and the second class chamber were achieved. The curves reflected the state of the double damper system in a complete cycle. The results show that the double damper system is responsive,and it can absorb the rebounding energy efficiently and assure the bit against the rock tightly when the piston impacts the shank next time.