During the separation process of outer cover and spacecraft body,the interaction force will affect the motion state of the spacecraft body.In order to explore the influence of the elastic separation of the outer cover on the spacecraft body.Firstly,based on the theory of multibody dynamics,Euler parameters are used to describe the attitude of rigid body.Then the dynamics equations including constraints of the system are obtained with a method of Lagrange multipliers by considering the interaction during the separation of rigid body.Finally,for the established dynamic model,the generalized α algorithm is used to solve the equation by time integration,and the corresponding calculation results are given for different conditions.The results show that the subsequent rotation state of the separated cabin changes regularly under different initial conditions.