Abstract: 304L/Q235B clad plates were prepared by explosive welding. In order to determine the best heat treatment process system, four kinds of heat treatment processes were designed. SEM and EDX were used to observe and analyze the microstructure and element diffusion of the 304L/Q235B interface. The micro hardness test was used to analyze the improvement degree of work hardening phenomenon.The results show that the interface of the composite is well bonded without delamination under different heat treatment processes.However, with holding temperature of620-700 ℃, the diffusion ofFe or Cr elements occurs near the interface of the 304L/Q235B clad plate, and the element diffusion degree is the largest with holding temperature 700℃. And the grain size near the interface of Q235B side is the largest (9-14 μm).The process with holding temperature 660 ℃ can decrease the work hardening degree of 304L/Q235B and keep the high hardness of steel plate. When the insulation temperature is 660 ℃, the results of the intercrystal corrosion test of the sample after heat treatment show that the sample has good corrosion resistance and the corrosion does not occur. Therefore, an insulation temperature of 660℃ is the optimal heat treatment process for 304L/Q235B clad plates.