AIM To semi-synthesize the similar compounds of (+)-praeruptorin A in order to discover new active compounds. METHODS From natural product Pd-Ib, three similar compounds of (+)-praeruptorin A were obtained purposefully by basic hydrolysis with KOH, reduction with NaBH 4, acylation with acids. RESULTS The structures of synthesized three similar compounds of (+)-Praeruptorin A were 3′( R )-tiglyloxy-4′-keto--3′,4′-dihydroseselin, 3′( S),4′(S ) -diangeloyloxy -3′,4′-dihydroseselin and 3′( S),4′(R )-divaleryloxy-3′,4′-dihydroseselin respectively. CONCLUSION This research work is first semi-synthesis of two known natural product and a new compound from the view of structural modification of (+)-praeruptorin A.