In order to improve the protection and maneuvering capability of armored vehicle, and reduce its weight, Using the 25mm ballistic curve canon and 105mm simulated Armor Piercing (AP) ammunition, influence of thickness, obliquity, and constraint condition of ceramic composite armor on the anti elastic performance was studied when subjected to the large inclination impact, DOP method was used to evaluate the anti elastic performance of composite armors. The results show, In the large inclination case, the ceramic composite armor protection factor of the same as the thickness of the increase reduced; ceramic composite armor when external flexibility than built-in anti elastic to high and built-in use can also select the appropriate thickness of the get a good anti elastic performance.