Abstract: The shaped charge-shaped charge type tandem warhead is one of the weapons which can effectively deal with the explosive reactive armor, whether the pre-warhead can reliably initiate the sandwich charge directly determines the success of the combat mission. Most of the former shaped charge warheads are made of metal liner, while this article is to explore whether the low-density material can be used as the liner material, so as to achieve the purpose of damaging explosive reactive armor. The damage characteristics of low density jet are studied with numerical simulation and theoretical calculation, and the numerical simulation results are compared with the theoretical calculation results. The results show that the low-density jet not only can reliably initiate the interlayer charge, but also has many advantages over the existing metal jet. Therefore, this paper has the scientific research value to provide reference for the engineering design.