The trimethylolpropane complex esters were oxidized by the oven at different temperatures and time.The kinematic viscosities,viscosity indexes and acid values of oxidized esters were tested respectively,and their change rules with oxidation temperature and time were obtained by fitting function.By testing the initial oxidation temperatures of the oxidized samples with the pressurized differential scanning calorimetry,calculating the activation energy,oxidation rate constant and halflife period,the effects of oxidation temperature and time on the oxidation stability of the oxidized samples were investigated.The results show that the variation trends of kinematic viscosity and acid value are close to logistic function curve,that is,they increase slowly at the initial stage,then grow rapidly and reach the fastest rate,and finally the rate is gradually decreased.The fitting parameters of viscosity and acidity function are closely related to oxidation temperature,which can be used to evaluate and predict the oxidation behaviors of oxidized esters.The trimethylolpropane complex esters keep high viscosity index after high temperature oxidation under different conditions,and their initial oxidation temperature and activation energy have not changed significantly,indicating that the trimethylolpropane complex esters still have excellent viscositytemperature properties and oxidation stability after oxidation.