Abstract: Series chamber is a new technology on the basis of the mature technology of solid propellant. It can improve the propeller’s kinetic energy through rebuilding the existed guns. It is important to the weapons’ performance improvement. The two phase flow model of the interior ballistics process of 140 mm series chamber gun is established and simulated by MacCormack scheme. In addition, the completed programming has been used to analyze the influence of main-secondary powder proportion，ignition delay of secondary power and piston mass on interior ballistics performance. The result shows that the new technology can improve propeller’s velocity while not adding chamber’s pressure.