The stability of large inclination angle is very important for the navigation safety of medium cruise ship. Taken 52 000 t medium Viking cruise ship as the research object, the stability theory of medium cruise ship is discussed. Based on the MAXSURF software, the stability check of large inclination angle of the ship is made, and the influence of waves on the stability of the ship is analyzed. The results show that the stability of the ship can meet the requirements of the specifications, and the navigation safety can be ensured. The research results can provide certain reference for the subsequent stability calculation and analysis of medium cruise ship.