Abstract: Metallurgical behaviours of steel combined 1Cr18Ni9Ti and 16MnR plate by explosive welding were studied with heat-treatment test.The conclusions showd that the width of visible carbon riching belt increases wavily,while the width of real carbon riching belt increases monotonously.The site where there is the maximum micro-hardness HV_m is near the visible carbon riching belt in stainless steel of 1Cr18Ni9Ti,and the maximum micro-hardness decreases when heating temperature T increased.Diffusion coefficient of element carbon and element chromium is determined.