According to the Japan Construction Mechanization Association standard JCMAS P045,A2F10 high pressure piston pump bench was established to study the oxidation durability of hydraulic oils with different antioxidant.The deterioration tendency of the hydraulic oil indexs,including sludge amount,oxidation stability and acid number,were detected at regular time in the process of bench operation.The results show that the variation trend of each index is not completely consistent,and there is a great limitation to evaluate the performance of hydraulic oils by using index boundary value.The weigh set and the fuzzy functions were designed to evaluate various performances of hydraulic oils by means of the fuzzy comprehensive evaluation method.The results show that the fuzzy analytical method is well correlated with actual condition,which provides a comprehensive and quantitative foundation for evaluating hydraulic oils used in the construction machinery.