To obtain the factors which affect the interior ballistic performance of desensitized high-energy nitramine gun propellants， the interior ballistic model was built through the closed vessel test and the 14.5 mm ballistic test. The correction coefficients were fitted by the particle swarm optimization algorithm. Then， the effects of muzzle velocity V₀ and maximum chamber pressure p_m by burning progressive factor Pr and charge mass ω were calculated and analyzed through the model theory. It was found that， the correction coefficient of burning rate χ and the utilization coefficient of propellant force η should be considered to predict the dynamic combustion characteristics of high-energy nitramine gun propellants by the classical interior ballistic theory. Compared with the case of static combustion， the relative increase of burning rate could exceed 10% in the dynamic combustion. Meanwhile， because of the energy dissipation， only about 80% of the propellant force can be effectively converted into the kinetic energy of projectile in the theoretical calculation. In result， the interior ballistic performance of gun propellants is affected by the coupling of Pr， ω， χ and η. As the major mechanism， the interior ballistic performance is significantly affected by the static combustion characteristics and the charge mass. There is a linear positive correlation between V₀ and ω， while p_m can be expressed by an exponential function of ω， and the coefficients in different correlations are determined by Pr. Nevertheless， with the different process conditions， the fluctuations of χ and η lead to the varying of interior ballistic performance， which increases the prediction deviation of the fitting correlation.