The prime function of lubricating additives are to strength or improve the effect of lubrication and the unti¡Vwear capability of lubricating base oil. This research use the self-development EHL tester to explore the effects of ellipticity parameter of ring , load, speed, concentration and particle of lubricating additives and slip ratio on the film thickness.. During pure rolling, the film thickness increases with increasing speed, but decreases with increasing load, and the effect of speed on the film thickness is more obvious than the effect of load. The film thickness of lubricating additives varies insiginificant when the concentration of lubricanting additives are 1% and 3%, but it increases evidently at 7%. The effect of concentration developes good function of lubricant just under the condition of high speed and low load. Smaller particle of MoS2 has better lubricant effect than that it bigger. The number of particle of MoS2 distributed over lubricant contact zone increase with increasing concentration . The film thickness is getting thick when the ellipticity parameter increases. The minimum film thickness and central film thickness will decrease when slip ratio increase. That means , slip ratio and film thickness have a inversive relationship. Furthermore, when slip ratio increases, the central film thickness will decrease rapidly, but the minimum film thickness will just have a gentle decrease. It still has lubricant effect under the roll-slip state when the particles are smaller. During pure slipping, the bigger the particles, the easier it piles up on the entering area, and it makes lubricating oil can not enter the contact area easily.