Numerical study of tip clearance on the aerodynamic performance of high loading transonic compressor was conducted, based on inlet stage of high pressure compressor of one civil high-bypass-ratio turbofan engine. The results show that the performance curves of mass flow versus pressure ratio and adiabatic efficiency go to left and down direction. The value of maximum mass flow, maximum pressure ratio and peak efficiency decreases gradually. There is a range of tip clearance from 0 millimeter to 0.3 millimeter between which the influence of tip clearance on performance character is trivial. When tip clearance is larger than 0.3 millimeter, the reduction of maximum mass flow shows the liner relation with the increasing of tip clearance. Besides, maximum pressure ratio and peak efficiency decline rapidly. The total pressure loss of the rotor increases 41 percent at 1.0 millimeter, compared to tip clearance of 0.3 millimeter. Tip leakage flow penetrates the shock wave, reacts with it and forms high entropy flow near the pressure side of the passage. When tip clearance is 1.0 millimeter, tip leakage flow leaks traverse from leading edge across the passage. The shock wave appears unconspicuous. Tip leakage flow affects main flow above of 80 percent span of blade.