Poly (propylene carbonate) (PPC), a biodegradable carbon dioxide-based copolymer with propylene oxide, has great potential applications in many areas for its excellent gas barrier properties, biocompatibility and processability. However, PPC is amorphous with low glass transition temperature and poor mechanical property, which limits its application. In order to restrain the segment motion of PPC and improve its Tg, based on the supramolecular science theory, polyvinyl alcohol (PVA) with multi-hydroxyl groups was selected to melt blend with PPC to build a unique physical cross-linked network structure by hydrogen bonding between hydroxyl groups of PVA and carbonyl groups or/and terminal hydroxyl groups of PPC. The interactions between PPC and PVA, and the effects of PVA on Tg, thermal behavior, morphology as well as mechanical properties of PPC/PVA composites were investigated. The shift of íO-H and íC=O in FTIR confirmed the formation of intermolecular hydrogen bonding between PPC and PVA. The improved compatibility between PPC and PVA significantly increased Tg from 34.1 oC of neat PPC to 44.0 oC of 70PPC/30PVA. This interaction also improved the thermal stability of the composite at low-temperature and during processing. The final performance of the composites got much better, the tensile strength increased from 10.5 MPa to 39.7 MPa at room temperature. Acknowledgments: This work was supported by State Key Laboratory of Polymer Materials Engineering (Grant No.sklpme2014-1-04).