The invention relates to a method for aged oil treatment through microwaves. The method includes the steps that 50-300 ppm of an aged oil treatment agent is added, then aged oil is put into a microwave reactor, nitrogen is turned off after air is replaced with the nitrogen, the microwave reactor is started, the reaction temperature is set to be 20-100 DEG C, the microwave power is 400-1000 W, thestirring rotating speed is 500-1700 r/min, microwave treatment time is 1-10 min, and microwave radiation is carried out; after microwave treatment, the aged oil is poured into a liquid separating funnel, and oil and water are completely separated after sedimentation. The method has the advantages of being high in aged oil treatment efficiency, environmentally friendly, free of pollution, short intreatment time, small in occupied area, low in investment, low in energy consumption, easy to control and the like.