Abstract: In order to ensure structural reliability of deployable structures in orbit, the hybrid analysis of its mechanism motion and flexible deformation is required. The basal equations for deployment analysis of deployable truss structures were thusly formulated. By using the generalized inverse theory, a new method was developed to the hybrid analysis of deployable truss structures with mechanism motion and flexible deformation. The coupling between these two motions was calculated, so the analytical process could obtain a high accuracy. Compared with conventional dynamics of flexible multibody system, the advantage of this new method lies in its ability to analyze the complex movement of large deployable truss structure effectively with a comparatively simple modeling process. The efficiency of the new method was verified by simulation program based on it.