The hydrazine hydrate was used as raw material to synthesize the trithanolhydrazine borate ester.The carried charges of the boron atom were calculated by Gauss for the compounds before and after hydrolyzation of the three kinds of borate esters,triethyl borate,triethanolamine borate,triethanolhydrazine borate.Exposure method was utilized to study the hydrolysis stability of three kinds of borate esters,respectively.Fourball friction and wear testing machine was used to investigate the friction and wear properties of trithanolhydrazine borate ester in rapeseed oil.The results show that the compounded triethanolhydrazine borate exhibits good hydrolysis stability,and the hydrolysis stability is 2 800 times higher than that of triethyl borate and 2.3 times higher than that of triethanolamine borate.Under low load,the trithanolhydrazine borate ester has good extreme pressure,friction reducing and antiwear properties.XPS and SEM were used to investigate the elements composition and the structure of boundary film formed on the steel ball surface.The results show that the borate esters additive is adsorbed on the steel ball surface,and a complicated lubricating film composed of the deposited film of B2O3 and the adsorption film of nitrogen is formed to prevent further friction and wear of the steel ball.