Abstract: Based on production mechanism of multipactor effect, multipactor proofing design of satellite-borne microwave high power modules is introduced. Many measures are taken to improve multipactor threshold of microwave active circuits. The validity of multipactor proofing design is proved by vacuum multipactor experiment finally. Based on it test data of microwave high power modules are offered. The module is applied in integrated solid-state transmitters on satellite-borne radar. Its output peak power is greater than 500W and it has good environmental adaptability in vacuum.