TiNi alloyed layer was prepared on surface of Ti6Al4V substrate by plasma surface alloying process. Micro-structure, composition distribution, phase structure and hardness distributing of TiNi modified layer were analyzed. Tribological performance of TiNi alloyed layer and Ti6Al4V substrate was observed by Pin-on-disc test. The results indicated that surface microhardness of TiNi alloyed layer was about 620HV. Coefficient of friction (CoF) and relative wear rate (RWR) of TiNi alloyed layer were lower than Ti6Al4V substrate, and wear resistance of TiNi alloyed layer was improved obviously. The wear mechanism of Ti6Al4V alloy is abrasion and adhesion wearing, while TiNi alloyed layer shows abrasion wearing.