Abstract: The influence of the parameters on structure and properties of chromium -plating' s grooved surface strengthened by plasma arc had been studied, and the interface strengthening mechanism had been analyzed. The results indicate that the heat input has an obvious effect on the quality of plating.Too little heat input is difficult to achieve the metallurgical bonding between plating and substrate, and too much heat input can cause over-heating which makes serious grain growth near the plating and reduces plating' s hardness and quality. It is possible to obtain the best results by using reasonable rifling rib, hatching rib, and the reverse side process conditions. The EDX results show that Cr and Fe can be mutually diffused in plating' s interface, and substrate near the interface takes place martensite transformation. Phase transformation hardened layer is formed between plating and substrate to achieve metallurgical bonding.