For efficiently simulating and analyzing the characteristics of radar target echo, a digital simulation method of modeling and designing radar echo is proposed. By analyzing theory of high resolution monopulse radar, radar target echo simulation system frame is designed and decomposed to several modules. Aiming at every module, digital model is set up and achieved by computer software. Simulation results show that the method can model the three-channel range profile echo of radar target, which can provide guidance for monopulse track data processing.