The multipactor effect is an electron discharge which is exerted by a force on primary free electrons in vacuum and driven by electromagnetic fields between dielectric or metal surfaces. It will result in serious consequences such as rising noise level, damaging component surfaces, increasing voltage standing wave ratio of transmission system, and even permanent failure. Thus it becomes a bottleneck problem in developing high power microwave components (MCs) for satellite. With the higher power of satellite, it is essential that some of MCs should measure multipactor threshold due to lack of appropriate manufacture and storage on ground. Current methods for detecting multipactor are introduced and analyzed, such as close to carrier noise, harmonic noise, and microwave nulling method. Recent years, automatic and digital characteristic method for detecting multipactor as well as safety is proposed. Automatic nulling method for multipactor detection (MD) is presented.