Abstract: In order to analyze the process of launching interior ballistics of projectile better, the classical projectile launching interior ballistics model and state equation of gunpowder gas was introduced into the finite element calculation through the secondary development of LS-DYNA. The interior ballistics process of a projectile was simulated by Lagrange method and the launch combustion mechanics process of projectile motion was simulated successfully. The simulation results show that the curve of velocity projectile, overload and ballistics pressure obtained by numerical simulation agree with the classical curve. At the same time, the numerical simulation solved the classical interior ballistics problem which is unable to obtain the projectile stress and dynamic strength etc.