Abstract: To evaluate the crater damage effect of cylinder charge contact explosions on steel fiber reinforced concrete (SFRC) structures, a numerical model of an SFRC target was developed by the coupling method of smooth particle Galerkin and structured arbitrary Lagrange-Euler (SPG-S-ALE). This coupling method effectively simulates the extreme deformation, fragmentation, and fluid-structure interaction characteristic c of near-field explosions. The validity of the simulation was verified through comparison with experimental results. On this basis, a systematic investigation was conducted to analyze the failure modes and damage extent of SFRC targets under the combined influence of charge mass and charge length-to-diameter ratio. Based on contact explosion theory and dimensional analysis, crater diameter coefficient K1 and depth coefficient K2 were introduced to formulate a predictivemodel that describes the front-face crater diameter and depth as functions of the effective charge mass. Results indicate that thenumerical simulation results are in good agreement with the experiment results, which verifies the effectiveness of the simulation method. The crater formation of SFRC targets is the primary failure mode under the combined effects of charge mass and charge length-to-diameter ratio. For a constant charge mass, increasing the length-to-diameter ratio from 1 to 5 reduces both the craterdiameter and depth by approximately 50%, highlighting the pronounced influence of charge geometry on damage localization. Within the range of effective charge mass up to 16 kg, K1 and /Kz exhibit a power-function decay with the increase in the effective charge mass. Conversely, the crater diameter and depth follow a power-law growth relationship with the effective charge mass. Moreover, under identical effective charge mass conditions, the damaging effect is more concentrated on the lateral expansion than on its penetration depth. The established predictive model enables rapid and reasonably accurate estimation of crater dimensions in SFRC with different strengths and under varying effective charge mass. The above research results can provide a valuable theoretical basis and a practical computational tool for the anti-explosion design and performance assessment of SFRC protective structures.