A folded waveguide Slow Wave Structure(SWS) with frequency range from 94 to 220 GHz is fabricated with Ultraviolet Lithographie Galvanoformung Abformung(UV LIGA) technology. For 94 GHz folded waveguide SWS, the accuracy is≤15 μm, the output power of 94 GHz pulse Travelling Wave Tube(TWT) with the microfabricated SWS is higher than 100 W. For 180 GHz folded waveguide SWS, the accuracy is≤5 μm, the output power is higher than 100 mW with bandwidth of 11.4 GHz. For 220 GHz folded waveguide SWS, the accuracy is≤3 μm, and the attenuation factor is 240 dB/m.