Generally, a hydraulic cylinder block which is one of a vehicle parts that plays Important role in excavator power transmission, has copper alloy separation phenomenon by sliding motion between metals in high pressure condition. In this paper, to solve this problem, the interfacial reaction layer of Fe-Cu With SCM440 and copper alloy is studied through the melting method. As the result of this study, it is found that the interfacial reaction layer of $1{mu}m$ created in the interface of Fe-Cu which has very strong physical bonding. It has been also confirmed that the melting method can improve life of the hydraulic cylinder block.