Abstract: For the case of constant stress wave input in analyzing a hydraulic rock drill, the value of stress waves which arrived the damping piston was calculated after many transmissions and reflections. Based on the transfer principle of stress waves in different media, a variable input model was deduced by the Fourier transform. The stress wave forms were tested by using a strain gauge and the variable input model was revised according to the test results. An equivalent rigid-flexible model of the accumulator and a structure model of the double damping system were established based on Newton's theory. The damping piston movement laws and the pressure change laws of order 1 and order 2 damping chambers were analyzed. The performance parameters of the double damping system were summarized and optimized by a multi-objective optimization method. The optimized results show that the flow of the damping system is 8.5 L·min^-1, the annular clearance is 0.017 mm, the inflation pressure of the accumulator is 2.3 MPa and the working pressure is 7.6 MPa.