A scheme of cabins auto-docking based on Stewart platform is designed for improving the efficiency and quality of missile's assembly. The subsystems and the process of this auto-docking scheme are expounded. A quantity of key technologies in the auto-docking process such as solving methods of coordinate-transformation matrix, principles of choosing feature points, measure of avoiding interference between cabins, calibration approach of Stewart platform's initial pose, judgment standard of docking mission accomplishment, and compensation approach for correcting pose error in auto-docking are analyzed. This method opens up a new train of thoughts for assembly technology of missile, and lays theoretical basis for the subsequent designing of real auto-docking system.