The traditional mortar interior ballistic characteristics analysis theory can not totally carry out the mortar interior ballistic characteristics analysis of impact firing in front of breech, establish the mortar interior ballistic model of impact firing in front of breech. Research the simulation and analysis of mortar interior ballistic character of impact firing in front of breech. Realize the analysis and calculation of mortar interior ballistic by Matlab software platform. The simulation results show that the analysis is effective and feasible and it can give theoretical support for further interior ballistic design.