WC/SS316L composite depositon layer was successfully prepared on the 316L substrates by the supersonic laser deposition (SLD) technique. The deposition behavior, interfacial bonding, microstructural characteristics and electrochemical failure mechanism of the particles in these prepared composite depostion layers are analyzed. The results show that, due to the softening effect of laser irradiation, the SS316L particles show an excellent plasticity deformation ability in the high-speed impact process and can be effectively deposited. Under the combined actions of laser irradiation and plasticity deformation of high-speed particles, the SLD layer has a better interfacial bonding behavior than the deposition layer prepared by the cold spray (CS) technique. The micro-hardness of SS316L particles in deposition layers is obviously higher than that of the original powder, which is attributed to the working-hardening produced within plasticity deformation of high-speed particles. Moreover, the WC/SS316L interface is prone to electrochemical failure.