The invention provides a vacuum sealed valve leakage rate test system and method. The system consists of a first vacuum pump set and a second vacuum pump set, a leak detector, a vacuum chamber, a vacuum valve test cover, a pressure gauge, a standard leak hole, vacuum gauges, a gas source, and a first vacuum valve, a second vacuum valve, a third vacuum valve, a fourth vacuum valve, a fifth vacuum valve, a sixth vacuum valve, and a seventh vacuum valve, wherein the first vacuum pump set is connected to the vacuum chamber through the first vacuum valve, and the leak detector is connected to the vacuum chamber through the second vacuum valve. The vacuum chamber is connected to one ends of the vacuum gauges, the third vacuum valve and the fifth vacuum valve respectively. The other end of the fifth vacuum valve is connected to the standard leak hole. A tested vacuum valve is installed in the vacuum valve test cover, one end of the tested vacuum valve is connected to the other end of the third vacuum valve, and the other end is respectively connected to the fourth vacuum valve and the pressure gauge. The gas source is in connection with the vacuum valve test cover through the sixth vacuumvalve, and the second vacuum pump set is in connection with the vacuum valve test cover through the seventh vacuum valve respectively. The system and method provided by the invention realize quantitative test of the vacuum valve local leakage rate and total leakage rate, and greatly improves the measurement uncertainty of vacuum sealed valve leakage rate.