Prefabricated buildings are considered to be an important basis for realizing the "Carbon peak, carbon neutral". However, few studies have systematically assessed the carbon emission reduction of different prefabricated components. According to the LCA theory, a P-GPS-LCA model is developed for evaluating carbon emission reduction potential of components. Eight different components, four prefabricated and one cast -in -place buildings are chosen for case study. The results indicate that carbon emissions of stair, balcony, composite slab, air conditioning slab, internal wall, external wall, external wall with window, external wall with door were significant variations. Carbon emissions of the prefabricated buildings were lower than that of the cast -inplace building. Carbon emissions in the production, transportation, and construction stages accounted for approximately 96.42 %, 2.69 %, and 0.89 %, respectively, with the majority of carbon emissions originating from rebar and cement. In addition, the higher prefabricated rate, the less carbon emissions. There was obvious linear positive correlation between carbon emissions and prefabricated volume, and cost. This study provides a scientific evaluation method and a solid data foundation for carbon emission research of prefabricated buildings.