An efficient and straightforward synthesis of beraprost sodium was developed with dicyclopentadiene as a starting material, a one-pot reaction product 5 as key intermediate and the Prins reaction and the Homer-Wadsworth-Emmons reaction as key steps. The structures of the key intermediate and the target compound were confirmed by H-1 NMR, C-13 NMR and MS. The purity of beraprost sodium identified by high performance liquid chromatography(HPLC) was identical to that of Japanese Pharmacopoeia(16th). This development will be used for the industrial synthesis of beraprost sodium.