The trimethylolpropane trioleate(TMPTO)synthetic lubricant was oxidized by the oven under 95,135,175 and 250 ℃,the kinematic viscosity and acid value of TMPTO were tested at different oxidation time responsively.By fitting the curves of kinematic viscosity and total acid number with oxidation time at different oxidation temperatures,the relationship between thermal oxidative behavior,the oxidative time and the oxidative temperature was determined.The thermal oxidation products and their performances of TMPTO at different oxidation time were determined by FTIR and DSC.The results suggest that the total acid number and the logarithm of kinematic viscosity of TMPTO synthetic lubricant tend to increase linearly with the oxidation time at a certain temperature,and the linear slope is bigger with the oxidation temperature increasing.The oxidative inducing temperature of TMPTO is reduced with the increase of oxidation temperature and oxidation time.FTIR analysis indicates that hydroperoxides and alcohols are produced during the oxidative process.