The aim of the current research is to investigate the ballistic performance of the sandwich structure consisting of aluminum, glass/epoxy and elastomer composite, as well as the effect of adding a composite layer and sandwiching the structure. The investigated structure is a 4-layer structure including two layers of T-6061 aluminum as external surfaces, a glass/epoxy composite layer including 6 layers of woven glass fabric and a layer of elastomer mixed with natural rubber. The purpose of building such a structure is to benefit from all the mechanisms of energy absorption in high speed impact. The experimental part was done using a gas gun device and the numerical part was done using LsDyna software. In the following, the damage mechanisms of different layers and between layers have been investigated experimentally and numerically, and after that, the improvement of the ballistic performance of the structure compared to the two-layer structure of elastomer and aluminum has been investigated through the output speed of the impactor.Also, the efficiency of the 4-layer structure at different input velocities has been investigated, and by considering the absorbed energy, the optimal critical speed for the best performance is obtained