Furan-2,5-dicarboxylic acid was synthesized from furoic acid by esterification, chloromethylation, hydration and oxidation, the important process parameters in each step was also optimized. The optimal reaction conditions were obtained as follows: the time of esterification was 10 hours, the temperature of chloromethylation was 35~40 ℃, n(sodium hydroxide)/n(methyl 5-chloromethyl- furan-2-carboxylate) = 2.1 : 1 in hydration, pH = 7~8 in oxidation, the total yield was 47.5 %. Under the optimized conditions, the synthetic method of furan-2,5-dicarboxylic acid was successfully carried out three times in 20 L reactor and the average yield could reach 47.3%, and the purity of the product was over 99.4%.