In order to improve the nitrogen explosion type hydraulic impacter stability in the field of highway cement,the mathematical models of return movement,impact piston movement of the nitrogen explosion type hydraulic impactor were established.The simulation model of the piston movement was set up by using numerical calculation platform Simulink.The results show that the acceleration of the piston monotonically decreases at stroke;the acceleration of the piston decreases firstly then increases at return.The cooperation of the accumulator nitrogen chamber and the hydraulic system obviously improves the stability of the speed control.Taking a small hammer with nitrogen explosion type hydraulic impacter as example,the stroke and return maximum speeds under different hydraulic system pressures were measured.Through comparing test results with simulation,the relative errors of the stroke and the return speeds are 13.3% and 2.6% respectively.