The effect of rotating speed and working pressure on the hydrostaticand hydro dynamic pressure distribution of the oil lubrication film in the internal gear pump has been analysed in this paper. The hydro dynamic pressure distribution is calculated based on the Renolds Equation which is solved by the finite difference method (FDM). Meanwhile, the hydrostatic pressure distribution is computed based on the hydraulic resistance network model. The calculation results pointed out that the rotating speed and working pressure have a great effect on the hydrostatic and hydrodynamic pressure distribution. These results are the background for further study to improve the stability, working efficiency, and lifespan of the internal gear pump.