The process of a concrete target subjected to a tandem warhead was studied by means of field testing and numerical simulation. First, field testing of a shaped charge impacting the concrete target was carried out, in which the concrete targets included normal strength concrete and ultrahigh performance concrete. Then, the rigid projectile was used to penetrate the damaged concrete targets experimentally. Numerical simulation was adopted to simulate the two stages of a tandem warhead penetrating into the concrete targets. The combined effect of penetration and explosion in the open literature was also reproduced by simulation. By comparing the depth of test data and simulation results, the accuracy of the algorithm, material models, and corresponding parameters was proven. Finally, the numerical simulation method was adopted to simulate the process of a tandem warhead damaging a concrete target, including shaped charge impaction, penetration following the rigid projectile, and explosion inside the concrete. As seen from the comparative results, the parameters used in numerical simulation can appropriately describe the concrete damage, and the tandem warhead can effectively improve the damage degree of concrete targets. The greatest influence of concrete strength on the damage subjected to a tandem warhead is the stage following projectile penetration. The conclusion of this paper can provide important reference significance for the design of tandem warheads and protective engineering.