Abstract: Aim To study the actual combustion law of deterred propellant charge in bore. Methods A doublebase deterred propellant was prepared, the shooting experiment was performed in a big caliber gun, the actual combustion law of this deterred propellant charge in bore was studied by using the potential equilib- rium method of interior ballistics. Results The parameters of deterred propellant charge at potential equilibrium point will move backward after using the deterred propellant charge . The formation rate of burning gas of deterred propellant is a cubic function or quadratic function. The combustion velocity function can be expressed by an exponential function in which the argument is the relative pressure impulse. Conclusion it is feasible in bore to use the potential equilibriurn method of interior ballisticse. This study lays the foundation for further studying the coated- propellant charge technique and establishing its interior ballllstic solution.