Radiation effects and radiation mechanism of Micro Electromechanical Systems(MEMS) accelerator are summarized, which indicates the importance of MEMS radiation effect and hardening techniques study. The radiation sensitivities of different types of MEMS accelerator are introduced, as well as the degradation mechanism of radiation effects, radiation damage of different materials and Si radiation effect. The international radiation experiments about MEMS accelerator are emphatically analyzed, and the trends of radiation hardness of MEMS accelerator are put forward.