On the basis of full analysis of the working principle of hydraulic breaking hammer of Nitrogen explosion chamber, the nonlinear mathematical model of the hammer was built. The hydraulic system model of hydraulic breaking hammer was prepared using DSHplus. Parameters of the model were set referencing to the user’s manual provided by manufacturer of the hammer. The results show that the errors of each item of parameters between experimental data and simulation result are all within 10%, which prove the simulation model built is correct.