Electrostatic discharge (ESD) suppressor is a kind of electrostatic discharge circuit, designed for protection of RF and microwave frequency band ICs. The theoretical model of ESD suppressor is present, and the capacitor, electric field and charge distribution of ESD suppressor with three different structures are analyzed through time-domain moment method (TDMM). The result shows that maximum electrical fields in discharge moment of all the there models are all higher than threshold field of air breakdown. The maximum electrical field is generated by curvature radius suppressor, while zigzag suppressor can generate multi-point breakdown which benefit for system design reliability.