In order to further improve the lubricating property of coconut oil,the intermediate was synthesized in the first esterification of trimethylolpropane with adipic acid,and then esterified with coconut oil fatty acid to prepare the titled complex ester.The FTIR spectrum,rheological properties,thermal-oxygen stability,tribological characteristics,hydrolytic instability and marine microbes degradation of the complex ester were investigated.The results show that the complex ester exhibits good rheological properties and thermal stability,whose viscosity is 114 mm2/s at 40 ℃,viscosity index is 159,pour point is -6 ℃,and onset temperature of thermal decomposition is 300 ℃,adapting to a harsh working condition.It possesses fine tribological characteristics,whose maximum nonseizure load is 2.6 times as great as that of coconut oil,and good sensitivity and matching characteristics to the compounded additive,Zinc dialkyl dithiophosphate and octadecylamine.Its hydrolytic instability is higher than that of coconut oil,and the degradation rate by marine microbes in 14 days is greater than 80%.The as-prepared complex ester is a kind of green ester lubricants with excellent properties.