Abstract: Internal charging-discharging is one of the primary space environment effects, to threaten the safety of medium earth orbit and geosynchronous orbit satellites. At the present time, study of internal charging-discharging is mostly about dielectric material, and the experiment facility and computer simulation tools can not deal with 3D satellite structure. Then to focus on satellite components is helpful for engineering. A 90Sr-90Y disk source was employed to charging some solar array drive assembly slip ring samples, and the surface voltage and electrostatic discharge were measured and compared each other. The space distributions of electric field and potential in the samples were got via Monte-Carlo method and finite element method. The results are also helpful for design of solar array drive assembly.