The ratio of Fe-Al compound at the bonding interface of solid steel plate to Al-7graphite slurry was used to characterize the interfacial structure of steel-Al-7graphite semi-solid bonding plate quantitatively. The relationship between the ratio of Fe-Al compound at interface and bonding parameters (such as preheat temperature of steel plate. solid fraction of Al-7graphite slurry and rolling speed) was established by artificial neural networks perfectly. The results show that when the bonding parameters are 516 ℃ for preheat temperature of steel plate, 32.5% for solid fraction of Al-7graphite slurry and 12 mm/s for rolling speed.the reasonable ratio of Fe-Al compound corresponding to the largest interfacial shear strength of bonding plate is obtained to be 70.1%.This reasonable ratio of Fe-Al compound is a quantitative criterion of interfacial embrimement, namely, when the ratio of Fe-Al compound at intefface is larger than 70.1%.interfacial embrittlement will occur.