Abstract: To further study the influencing factors of the performance of water lubricated single-screw air compressor, a water lubricated single-screw air compressor was designed and manufactured, and an experimental system was set up to investigate the effects of rotation speed, discharge pressure and water injection flow rate on the performance of the water lubricated single-screw air compressor. Results show that increasing the rotation speed can reduce the leakage and improve the performance of the compressor. When other working conditions remain unchanged and the water injection flow rate is increased, the water-gas ratio of the compressor can be improved, and the heat exchange between water and gas and the sealing effect of the compressor can be enhanced, so as to improve the performance of the water-lubricated single screw air compressor. When the rotation speed is 3000r/min and the discharge pressure is 0.50MPa, the increase in the water injection flow rate from 50L/min to 80L/min reduces the specific power of the compressor, improves the volume efficiency, and improves the adiabatic efficiency by 0.26kW/(m³·min^-1), 5.15%, and 2%, respectively. Since the viscosity of water is much less than that of lubricated oil, the water-gas ratio is higher than that of oil-gas in the same working condition in order to ensure the performance of the compressor. Based on the research in this paper, when the discharge pressure is in the range of 0.50MPa-0.65MPa at the rated rotation speed of 3000r/min, the recommended water-gas ratio range is 2.94%-3.48%.