Abstract: A numerical study was simulated on the impact of inlet dryness on the aerodynamic performance of supercritical carbon dioxide compressor, and the morphological feature of tip clearance flow under different inlet dryness was emphatically compared and analyzed. Results show that with the decrease of the inlet dryness, the mass flow rate at the maximum efficiency scenario, the peak efficiency, the pressure ratio and the surge margin increase. At design flow rate and low flow rate conditions, the efficiency decreases with the decrease of inlet dryness. At the condition of high flow rate, the efficiency increases with the decrease of inlet dryness. When tip clearance is 5% of inlet blade height at the same conditions, the smaller the inlet dryness is, the stronger the tip leakage flow will be, and the "secondary leakage" is easier to be formed.