A strategy of formation transformation control for multiple automatic underwater vehicle (multi-AUV) systems based on the priority model is presented in this paper. Firstly, the model of leader-follower multi-AUV formation is established. Then, the priority model is adopted to solve the problem of multi-AUV formation transformation. Next, the back-stepping based sliding motion controller (BSMC) is designed for multi-AUV formation, which can deal with the uncertainty of mismatch and ensure real-time performance. Finally, the simulation results are presented to verify the effectiveness of the proposed algorithm.