Abstract: In order to improve the theoretical system of piston pump performance analysis, the effect of different speed on the oil film lubrication properties of piston pair in eccentric state was studied. Firstly, the mathematical models of the plunger pair oil film thickness field, pressure field and temperature field were built. Then, the Reynolds equation and the energy equation were discretized used the finite volume method and solved by successive over relaxation (SOR)algorithm. Finally, the oil film properties of the plunger pair were simulated by MATLAB software. The effect of speed on the pressure field and temperature field of the oil film in the oil pressure area in one cycle was obtained. The research results indicate that the eccentric load of the plunger produces a squeeze effect. As the speed increases, the peak value of the oil film pressure increases more rapidly. When speed is 3000r/min, the peak pressure reaches 63.87MPa. The shape of the temperature field of the plunger pair oil film at different speeds is basically the same. The higher the speed is， the greater the plunger eccentricity is, and the 
faster temperature increases. When speed is 3000r/min, the local temperature peak at the oil film reaches 62.2℃. The results provide a theoretical basis for further improving the lubrication performance of the plunger pair of the plunger pump.
Key words: positive displacement pump; plunger pumpspeed; oil film properties; successive over relaxation(SOR) algorithm; squeeze effect; temperature peak