The control of carbon emission in construction industry becomes an important research topic with the aggravation of global warming, hence the need for research of calculation and monitoring of carbon emission in construction sites. In this paper, the existing carbon emission calculation methods were combed out, and the characteristics of them were summarized. Then, the framework of real-time monitoring system of carbon emission in construction sites combined with cyber-physical systems (CPS) technology was proposed. The calculation boundary and calculation logic of carbon emission were definded, and the real-time carbon emission monitoring system was developed from hardware system and software system. Through the effective coupling of wireless sensors, servers, databases and clients, the system finally accomplished real-time monitoring and data analysis of carbon emissions in construction sites.