The aviation lubricating oils of JC-1,JC-2,928N and 928U with poly alpha olefin as base oil were analyzed using GC/MS/MS technology,and the method to improve aviation lubricating oil thermal oxidation stability was put forward.Poly alpha olefin base oil and the antioxidants in the base oil were analyzed.The change of oil organic matter was researched by solid probe time of flight mass spectrum analysis technology,which provided scientific basis to control the oil quality decay and oil discoloration problem.