Hypoxia is a major inherent characteristic for the most of solid tumors and produces severe treatment resistance to radiotherapy and chemotherapy of tumors and often results in poor prognosis.1-H-1-(3-18F fluoro-2-hydroxypropyl)-2-nitroimidazole(18F-FMISO)is a specific hypoxia imaging agent and has been applied into clinic to evaluate tumor hypoxia status and guide treatment plan of radiotherapy and chemotherapy by PET/CT.A new automated synthesis procedure of 18F-FMISO was developed by modifying the Explora FDG4 module and taking 1-(2’-nitro-1’-imidazolyl)-2-O-tetrahydropyranyl-3-O-tosyl-propanediol as labeling precursor in this study.Two-pot reaction was adopted to assure good separation of the final product via solid phase extraction based upon combined Sep-pak cartridges instead of HPLC.This fast reliable preparation route of 18F-FMISO could be completed in about 50 min with about 55% of radiochemical yield and over 98% of radiochemical purity.