Abstract: In order to satisfy the requirement of attitude control system design for gravity gradient stabilized satellite, this paper presents the coupling dynamics equations of satellite attitude and gravity gradient boom deployment. Considering the boom structure, the deformation energy method is introduced to establish the dynamics equation of the gravity gradient boom. As an example, dynamics of micro-satellite “Tsinghua-1” during the boom deployment is analyzed under different initial conditions. The conditions for proper attitude acquisition after boom deployment are obtained from the simulation.