Abstract: The effect of Ni addition on microstructures and wear under oil lubrication of ZA27 alloy was invesitgated. The results show that with 0.4%Ni addition, the dendrites are refined effectively, many particles with enriched Ni appeared in eutectic of ZA27 alloy. Under load higher than 1 000 N, the wear resistance of ZA27 alloy with Ni addition was significantly better than that of ZA27 alloy, especially for higher loads. At 1 000 N, with the increase of Ni addition amount, the wear resistance and subsurface thickness of ZA27 alloy firstly increased and then decreased. The main wear mechanisms varied with Ni addition amount, i.e. severe plastic deformation accompanied with adhesion wear, a mild cutting wear accompanied with plastic deformation, a ultra-mild regime of microcutting wear accompanied with adhesive wear, and a relative severe regime of cutting wear and adhesive wear. The hardened surface layer can improve the wear resistance of ZA27 alloy.