Abstract: According to thermodynamics theory, the impact force for separation of the launch vehicle fair is calculated. The test data for a single explosive bolt and the method of direct integral dynamic response are combined to simulate the dynamic load on sixteen bolts during separation of a Φ3800 faiingr. Consistent results are obtained, which agree very well with the experiment results. It is shown that the methods used in this paper can improve the precision and eliminate the ill-conditioned influences.