The effects of density and impact intensity on combustion properties of energetic thermoplastic elastomer(ETPE) gun propellants were studied by closed bomb test, high pressure flameout set, scanning electron microscopy (SEM) and physicochemical property test. The results show when the actual density of ETPE gun propellant (BAMO/AMMO based) is 84% more than that of theoretical density, with increase of the density, the burning rate, burning-rate coefficients and pressure exponent of ETPE gun propellants reduce. There is a adverse correlation between the impact intensity and the burning rate and pressure exponent of ETPE gun propellants.