The hot-compression bonding process is a new technology used to manufacture heavy forgings which can avoid the size effect caused by the traditional casting process. In this new technology, the surface state of substrates is a key factor to guarantee the quality of bonding joints. At present, the influence of different surface states on the quality of interface bonding is uncertain. Therefore, the effect of surface state on the bonding quality of interface was studied in this paper for the first time. Different methods such as optical observation and elemental analysis were used to composite characterize the surface state. Furthermore, the microscopic morphology of the cross-section samples derived from the bonding joints was used to analyze the quality of interface bonding. The influence of the surface state on interface bonding quality was obtained by analyzing the relationship between the surface state and interface bonding quality. The results show that 90% of the interface bonding area can achieve a seamless interface effect after the bonding of two relatively clean substrates, which means that a clean surface state can greatly improve the bonding quality of bonding joints. This study can help to understand the relationship between the surface state of the substrate and the bonding quality of the interface. It is beneficial to guarantee the interface bonding quality of the substrate and is of great significance to further improve the quality of the joint.