Abstract: To predict the pyroshock environment of spacecraft, an explicit FEM method is used to simulate the load force function. To study the deployment of the solar array, a model is established to analyze the pyroshock characteristics of different pulse functions loading on the spacecraft. Comparison with the ground test data shows that a reasonable load force function can be obtained by the superposition of several simple pulsed functions, with a consistent prediction result as compared with the ground test data. The paper proposes a method for determining the load force function of explosive devices without complicated modelling of the pyrotechnics, which may serve as a basis for the subsequent prediction of the pyroshock environment of spacecraft.