Abstract: Aiming at improving the effectiveness of the experimental multipactor tests, three different methods of electron seeding based on radioactive sources, ultra violet light sources and electron gun are investigated. Advantages and application range of these methods are introduced and compared. Then, two radioactive sources, β decay and γ transition, are particularly discussed, and their characteristics of electron seeding are quantitatively analyzed. The obtained result shows that both methods can be used to generate seeding electrons that can penetrate millimeter-level aluminum walls of microwave devices, suitable for electron seedings in high-power multipactor tests for microwave components.