By means of high temperature thermal oxidation accelerated simulator,the hightemperature operating environment of PAO aviation lubricating oil in the presence of copper was simulated,and the variation of appearance,viscosity and acid value of PAO was analyzed before and after adding copper by contrast.The micro composition of samples under different temperature was detected by GC/MS,and the reason of the physical and chemical properties changes of PAO was analyzed according to the material structure.The result show that the high temperature cracking of PAO is accelerated in the presence of copper,some chromophores are produced,which accelerate the oxidation deterioration of PAO and make oil products kinematic viscosity reduced.The formation of acidic material results in the increasing of the acid value of PAO.The analysis results of GC/MS show that,the presence of copper will accelerate the oxidation and cracking of PAO,promote the formation of hydrocarbon molecules with less carbon number,and the substances such as unsaturated hydrocarbon containing double bonds and oxycompounds.So the viscosity of the oil sample is decreased,the acid value is increased and the color is deepened.