According to the force of connecting place and feature of the locking device，the possibilities of loosening in the connecting place of the satellite and launching vehicle are studied in this paper. The formulae of preforce the wrapband needs are obtained by applying the theory of a general force system and friction. The distribution of wrapband stress is analysed，and the method for solving the nonuniform distribution of the stress is put forword. Compard with the experimental results of the two types of the device，it is proved that the method of analysis and the formulae of calculation are reliable. The conclusions provide a basis for designing the locking structure of a satellite and launching vehicle with wrapband.