Abstract: Based on the tribological testing and EDS analysis of the friction surface film,the interaction mechanism of borate, chlorinated paraffin and zinc dialkyldithiophosphate (ZDDP) additives was studied. The results show that organic borate functioned as a friction modifier. The concentration of chlorinated paraffin affected the interaction with borate. Calcium petroleum sulphonate served as dispersing agent worsened the antiwear property of borate. ZDDP and borate had a competitive action on the metal surface in the process of friction. This improved the antiwear property of borate. There existed synergistic effect among organic borate, chlorinated paraffin, and ZDDP.