Nano-metric magnesium silicate and zinc silicate with particle size of about 50-70nm were prepared in water by the method of chemical deposition. The antiwear and friction reducing abilities of the nano-silicates,as well as their composites with oleic acid tri-ethanolamine(OATEA) ,were evaluated on a four-ball friction tester. The topographies and tribochemical features of the worn surfaces were analyzed by scanning electron microscope(SEM) and X-ray photoelectron spectroscope(XPS) . Results show that nano-silicates alone provide poor antiwear and friction reducing abilities in water,but exhibits excellent synergism with OATEA in reducing friction and wear. The synergism in reducing friction and wear between nanosilicates and OATEA does exist almost regardless of particle sizes and species,and may be attributed,on one hand,to the formation of an adsorption film of OATEA,and,on the other hand,to the formation of tribochemical species of silicon dioxide and iron oxides on the friction surfaces. Tribo-reactions and tribo-adsorptions of nano-silicates and OATEA would produce hereby an effective composite boundary lubrication film,which could efficiently enhance the anti-wear and friction-reducing abilities of water. The antiwear and friction reducing abilities of the nano-silicates, as well as their composites with oleic acid tri-ethanolamine (OATEA), were evaluated on a four-ball friction tester. The topographies and tribochemical features of the worn surfaces were analyzed by scanning electron microscope (SEM) and X-ray photoelectron spectroscope (XPS). Results show that nano-silicates alone provide poor antiwear and friction reducing abilities in water, but exhibits excellent synergism with OATEA in reducing friction and wear. The synergism in reducing friction and wear between nanosilicates and OATEA does exist almost regardless of particle sizes and species, and may be attributed, on one hand , to the formation of an adsorption film of OATEA, and, on the other hand, to the formation of tribochemical species of silicon dioxide and iron oxides on the friction su rfaces. Tribo-reactions and tribo-adsorptions of nano-silicates and OATEA would produce hereby an effective composite boundary lubrication film, which could efficiently enhance the anti-wear and friction-reducing abilities of water.