To evaluate oxidation stability of hydraulic fluids for construction machinery,using the A2F10 piston pump test bench,in simulated operating conditions of construction machinery,such as high temperature and high pressure or other conditions,the hydraulic fluid was circulated continuously in the test bench,sampled at regular time,and the situations of kinematical viscosity,acid number,sludge generating amount,oxidation stability and other items were detected to analyze the deterioration tendency.The test to different hydraulic fluids shows that the bench system can be used to estimate oil oxidation life.