OBJECTIVE: To analyze 18F-fludeoxyglucose injection by Silica Gel TLC method.METHODS: TLC was adopted in which 18F-fludeoxyglucose injection(A) and mixture solution of 18F-FDG injection-acetonitrile(5∶95,V/V)(B) were used as testing solution.GF silica plate and G silica plate were used as stationary phase,and the mobile phase was acetonitrile: water(95∶5,V/V).RESULTS: The main peak Rf of testing solution A had a great fluctuation;The main peak Rf of testing solution B was 0.38～0.40.Radiochemical purity of 18F-fludeoxyglucose was more than 98%,and the Rf of radioimpurity 18F-and the by-product 18F-fludeoxymannose stood at 0.0 and 0.78 respectively.CONCLUSION: When testing solution B,the process of silica gel thin-layer chromatographic analysis is stable and reproducible,and the results meets the requirements specified in USP and are independent of the category of silica plate.