Reynolds equations and one-phase model with N-S (Navier Stocks) equations are widely used to calculate pressure distribution in the liquid film. In most cases, negative pressure exits in the obtained results. In a water-flooded single screw compressor, it is necessary to investigate the pressure of water film along the whole tooth flank. A negative pressure may not be right, because that when the pressure is lower than the saturated vapor pressure, cavitation occurs. In this paper, we investigated the pressure distribution of the water film with cavitation model. Results were compared to the pressure distribution obtained by one-phase model using N-S equations. Results show that difference of pressure distribution obtained by the two models is very similar for the positive pressure distribution. For the negative pressure distribution, the saturated vapor pressure could be applied to replace the results obtained by one-phase model with very small errors. Therefore, one-phase model will be effective to simulate pressure distribution along the tooth flank by using the vapor pressure to replace the negative pressure