Abstract: Copper and nickel were permeated into the surface of TC4 alloy by plasma alloying technology. Using XRD, SEM and GDS, the morphology, composition and phase of the layer were analyzed. The antibacterial properties of the TC4 alloy before and after alloying were tested through plating method, and antibacterial mechanism was preliminary analyzed. Results show that an alloy layer bonding well with matrix with thickness about 7.5 μm formed on the surface of TC4 alloy after alloying treatment. The alloy layer contained about 40 wt.% of Ni and 8 wt.% of Cu, and the contents of Cu and Ni displayed a gradient descent along it′s depth. The antibacterial effect of the alloy layer to escherichia coli was obvious, so the treated TC4 show a good antibacterial property. The antibacterial mechanism was related to Cu.