The slurry of A1-20Sn alloy was prepared using electromagnetie-meehanieul stirring method. The bonding of steel/mushy A1-20Sn was conducted using casting rolling technique. The bonding parameters were 505℃ for preheat temperature of steel plate and 10mm/s for rolling speed. The interracial mechanical property and structure of steal/mushy Al-20Sn bonding plate were studied. The results show that the relationship between solid fraction of A1-20Sn slurry and interracial shear strength of bonding plate is S=52.9+0.998φ-0.0144φ2 (where S is interracial shear strength, φ is solid fraction). The largest interracial shear strength is 70.2MPa when solid fraction is 34.6%. The interface of bonding plate is made up of Fe-Al compound and Fe-A1 solid solution alternatively.