In order to verify the rationality of protective cover structure design in ammunition assembly and improve safety protection performance. The failure area of 15 mm thick protective cover is judged by theoretical calculation and statics analysis, and the improvement scheme of adding wall thickness to 30 mm, with two 100 mm *100 mm square vent is put forward. The influence of wall thickness and vent on the safety performance of protective cover is evaluated by dynamic simulation of explosion impact process. The results show that the optimized protective cover can meet the requirements of anti-explosion design without changing the shape size, thus preventing the injury to equipment and personnel under accident, and providing reference for the design of small size protective cover for large amount charging.