In diffusion-rolling bonding, bonding temperature is a key parameter influencing interface bonding strength. In this case, lab experiments were carried out in a vacuum furnace to simulate the diffusion-rolling bonding of steel sheet of polycrystal structures under different temperatures. Bonding strength and interlayer film thickness were measured. The relationship between bonding strength and “diffused interlayer” thickness λ was investigated. The effect of temperature on diffusion-rolling bonding was investigated. Diffusion mechanism was qualitatively discussed. Based on above diffusion mechanism, the transformation in phase structure and its effect on the diffusion coefficient under different temperature was also analyzed and compared with the experimental results.