Objective: By the study of the process of synthesizing the tracer of tumor cellular proliferation which was 3’-deoxy-3’-18F-flurorothymidine(18F-FLT), using BAThy-FLT-precursor and BOC-FLT-precursor, demonstrated that the BOC-FLT -precursor played an important role in improving the synthesis yield of 18F-FLT. Method: We cooperated with seven PET centers doing the research on synthesizing the radioactive tracer(18F-FLT) following the standardized protocols of the national multicenter clinical trial. Cyclotron(MINItrace, GE Healthcare) and fully automated synthesis system(TRACERlab FX F-N, GE Healthcare). The (5’-O-Benzoyl-2, 3’-anhydrothymidine) and {3-N-t-Butoxycarbonyl-[5’-O-(4,4’-dimethoxytriphenylmethyl)- 2’-deoxy-3’-the product of 18O(p,n) 18F, and then hydrolyzed. Product were purified by the HPLC, getting the 18F-FLT, radiochemical purity>95%. Results: Using BAThy-FLT-precursor to synthesize 18F-FLT, the mean synthesis yield is 10.1%. While using BOC-FLT-precursor to synthesize 18F-FLT, the mean synthesis yield is 23.2%. Conclusion: We found that BOC-FLT-precursor was easier to be marked by 18F-. The mean product yield was 130% more than BAThy-FLT-precursor. We also studied on the effect of some factors on product yield of 18F-FLT, including the ratio of alkali to precursor, the solvent of precursor, the hydrolyze method and operated method. As the collaborator in the domestic distributed in the different areas, it eliminated the regional difference on the product yield. The results of the research is a good guide.