 This paper investigated the mesody bonding process of a gap-slash-cl-20-slash-ap composite solid propellant, under uniaxial tension. It used the advantages of the material point method, MPM, and the finite element method, FEM, to analyze the numerical simulation results. The results showed that the numerical simulation results were in good agreement with the experimental results in terms of microcrack, cracking characteristics and the nominal stress strain curve of propellants. Furthermore, the influence of interface parameters on the stressed strain curve was also discussed. This paper provides valuable insight into the structural integrity problems of solid rocket motor charges and conserve, as a useful guide for future design and analysis efforts. This article was authored by Xiaoyong Bu, Xiangyang Liu, Chunying Dong, and others.