Abstract: In order to improve the utilization rate of energy, two composite plates can be obtained at one time by using a double-sided explosive welding device. With the help of LS-DYNA software and smoothed particle hydrodynamics, SPH-FEM coupling algorithm was adopted. Three-dimensional numerical simulations were made for the double-sided explosive welding experiment of stainless steel/ordinary carbon steel by selecting 304 stainless steel with the thickness of 3 mm, Q235 steel with 16 mm and emulsion explosives. The explosive welding window was calculated and established. The vertical displacement, collision pressure and collision velocity were analyzed, and the simulation results were consisted with the experimental results. The simulation results show that the composite quality is better under the thickness of 7 mm, while the welding failure may be caused by the excessive collision energy under the thickness of 10 mm. The simulation results were in accordance with the experimental results. The Gurney formula was introduced to predict the experimental results. The calculation results show that the prediction results of the Gurney formula are in good agreement with the experimental results, indicating that the SPH-FEM coupling algorithm and Gurney formula are effective for double-sided explosive welding of stainless steel/ordinary carbon steel.