Ultraviolet Lithographie,Galvanoformung and Abformung(UV-LIGA) is an attractive technique to fabricate THz vacuum electron devices including resonance cavities,electron beam tunnels and output waveguides. This paper studies the effects of the softbake,the exposure dosage and the postbake on SU8 models,highlighting the effect of the exposure dosage and its mechanics,and then obtains the optimized process parameters. The methods of SU8 removal are studied as well,and a 340 GHz all-copper Folded Waveguide(FWG) Slow Wave Structure(SWS) is fabricated.