Oil soluble lead oleate is synthesized in-situ in 200SN basic oil and characterized with FT-IR . Its tribological properties as friction reducing and anti-wear additives of lubricating oil are evaluated with four-ball and reciprocation tribo-tester. The results indicates that lead oleate have excellent anti-wear property, better wear-reducing efficiency and middling extreme pressure property. Wear scar surface is characterized with photoelectron spectroscopy (XPS)and scanning electron microscopy (SEM) for explaining friction reducing and anti-wear mechanism. Analytical results show that the additive could markedly improve tribological properties of 200SN basic oil by forming adsorbing film on steel-steel friction pair and part of film transforming oxidic film by means of tribochemical reaction.