Abstract: The thermodynamical stuty indicates that the synthesis of propylene carbonate (PC) from urea and propylene glycol is possible. The reaction process for synthesis of PC was investigated using ZnO catalyst. It was a stepwise process. At first, urea decomposed into isocyanic acid, which interacted with ZnO to form a relatively steady isocyanate species. Then propylene glycol reacted with isocyanate species to form hydroxypropyl carbamate (HPC), and the HPC lost ammonia to form PC. The catalysis of ZnO was striking in urea decomposition and the transformation of HPC to PC.