Abstract: The state equation of detonation product is an important method for estimating the working capacity of explosives. In order to fit the parameters of JWL state equation, experiments on flyers driven by explosives were conducted by using copper and tungsten, two metals with large impedance differences. The parameters of the JWL state equation of DNAN based melt-cast explosives (DNAN/RDX 40/60) under the condition of tungsten flyer were calibrated by trial and error method and LS-OPT software automatic calibration. The error of the calculated curve obtained by trial and error method was 16.86% compared with that of the experimental curve, and the error of automatic calibration was 3.04%. The parameters obtained by automatic calibration were used to simulate the process of driving the copper flyer, and the experimental curves were compared with those of the copper flyer. The error was 4.60%. The research shows that the LS-OPT software automatic calibration method can be used to calibrate the parameters of the JWL state equation of DNAN based melt-cast explosives. Compared with the traditional fitting method, it can avoid a lot of manual calculations and obtain more accurate results.