Based on the interior ballistic equation theory of land gun launch,and combined with the technique characteristic of underwater shaped charge cutter movement,the energy conversion mechanism of cutting movement and the dynamic response of interior component of the cutting frame have been comprehensively analyzed. The normalized mathematical model has been established for the numerical calculation of interior ballistics parameter variation characteristic curve. Through the simulation of the interior ballistics of a certain type of underwater cutter, the variation process of each parameter is analyzed quantitatively,and the feasibility of the short stroke shaped charge cutting scheme is demonstrated,which lays a theoretical foundation for the subsequent interior ballistics design and the optimization of charge parameters.