Abstract: To meet the requirements of the long time on obit storage of cryogenic propellant,a test system for the ground test has been built. By maintaining high vacuum and constant wall temperature condition,on orbit condition can be simulated. A temperature compensator is set up to shield the heat conduction loss in the neck tube of tank. The vacuum degree and the wall temperature in the system can be monitored,and the temperature distribution of the insulation system and the gas flow rate of the tank can be measured. In the 10 mm rigid polyurethane foam and 30 layers of multilayer insulation experiment,in the vacuum of 2×10^-3 Pa,boundary temperature of 96 K and 313 K,the measured daily evaporation rate of liquid nitrogen is 0.210%,and translated daily evaporation rate of liquid oxygen is 0.156%.