Abstract: Unlike the traditional oil-lubricated bearing, the water-lubricated bearing has unique advantages because of which lead it has important applications in all types of high-speed rotating machinery. Under actual working conditions, the lubrication water will inevitably mix with a certain amount of undissolved gas, which too will participate in the lubrication process. In this study, computational fluid dynamics (CFD) software Fluent was used to analyze the characteristics of the high-speed water-lubricated bearing and to investigate the influence of the amount of undissolved gas on the phase distribution of the gas phase, pressure peak value, and bearing performance. The full cavitation model and gas-liquid mixture model were employed in this study. The results show that in the highspeed water-lubricated bearing clearance, the gas phase is distributed in the divergence wedge, and the maximum gas volume fraction exists on the surface of the shaft; When the eccentricity is small, a certain amount of undissolved gas can offset the gas phase distribution in the bearing gap and reduce the load-carrying capacity of the bearing. However, the gas appears to have no clear influence on the pressure peak and the frictional power consumption. As the bearing eccentricity increases, the influence of the undissolved gas disappears gradually.