Abstract: To investigate the influence law of charge spacing on the damage effect of Q235 steel plates under contact explosion conditions, and provide a theoretical basis for the design of explosion-resistant armor structures and layout optimization of multi-point simultaneous initiation warheads, this paper takes JH-2 explosive and Q235 steel plate as research objects and adopts numerical simulation to study the damage effect of blast loads from dual explosion sources on steel plates under contact explosion conditions. Firstly, a numerical simulation model for contact explosion is established, and the accuracy and reliability of the model are verified by comparison with experimental results. On this basis, the coupling effect of shock waves generated by two charges after detonation and its influence law on the plastic deformation characteristics and plugging failure mode of steel plates are analyzed. The results show that with a constant total charge mass, the damage range of the two-point array expands with the increase of charge spacing, and the critical array spacing capable of forming complete plugging holes is 30 mm. Under contact explosion of the three-point array, the damage area presents a unimodal variation characteristic that rises first and then declines as the array spacing increases, and the optimal charge array spacing is 26.23 mm where the maximum damage efficiency of the target plate is achieved. The established Gaussian prediction formula has a goodness-of-fit of 0.9212, which can rapidly and quantitatively predict the steel plate damage area corresponding to any array spacing within the range of 12.6–50 mm. The research findings can offer theoretical basis and quantitative data support for the evaluation of coupled damage efficiency of dual charges under contact explosion and the design of explosion-resistant structures, and also provide references for the layout design of multi-point simultaneous initiation array charges.