Amphiphilic copolymer of 5-benzyloxytrimethylene carbonate (BTMC) with poly (vinyl pyrrolidone) (PVP) was successfully synthesized using immobilized porcine pancreas lipase (IPPL) or SnOct2 as catalyst. Hydroxyl terminated PVP, synthesized with 2-mercaptoethanol as a chain transfer reagent, was employed as a macroinitiator. The resulting copolymers were characterized by GPC, 1H NMR and IR. Increasing the BTMC/PVP-OH feed ratio ([B]/[P])resulted in the increase of Mn of corresponding copolymers and the decrease of Mw/Mn.Immobilized enzyme has comparable catalytic activity to SnOct2 for the copolymerization.