The influence of tip clearance on turbocharger turbine performance of passenger car gasoline engine was studied. Three types of tip clearance changes were designed, including the individual changing of impeller inlet tip clearance, the individual changing of trailing edge tip clearance and the synchronous changing of both. Different sizes were set for each type of tip clearance. Numerical simulation was then carried out under steady condition for the three types of tip clearances. The results show that the synchronous changing of impeller inlet tip clearance and trailing edge tip clearance has the greatest effect on turbine efficiency, output power and turbine exit temperature and the individual changing of impeller inlet tip clearance has the least effect. The influence of synchronous changing on turbine output power and exit temperature is basically the linear superposition of the individual effect of the two tip clearances. The effect of tip clearance on turbine flow capacity is unobvious. With the increase of clearance size, a high-value area of total pressure appears in the latter part of blade passage and the Mach number of impeller exit becomes large, resulting in the turbine efficiency decrease.