Abstract: By preseting asymmetric Ti/Cu interlayer,liquid-solid diffusion bonding of Ti(C,N)-based cermet and 40Cr was performed. The interfacial microstructure,joint strength and their effect factor were investigated. The results showed that, through preseting asymmetric Ti/Cu interlayer,the metallurgic bondings between Ti (C,N)-based cermet and Cu foil and between Cu foil and 40Cr steel can be achieved in liquid-solid diffusion welding, respectively. The phase at the interface of Ti(C,N)-based cermet has gradient distribution, forming Ti(C,N)-based cermet/TiAl₂/Ti₂Cu/TiCu/Cu foil structure. There exists large welding residual tensile stress and brittle TiAl₂ intermetallic compounds in the interface zone close to Ti(C,N) based cermet,being the key factor of restricting the strength of welded joint. By only using Cu foil as interlayer,it is difficult to join Ti(C,N) based cermet to Cu foil effectively in solid diffusion welding of Ti(C,N) based cermet even at the heating temperature of 1 223 K and the pressure of 20 MPa.