Using grey incidence analysis method, this paper analyzed the impact of various factors on the coordinated development of economy-society-environment system of Wanjiang urban belt to explore the mechanism of the coordinated development of regional economy-society-environment system. From 2011 to 2018, in the coordinated development of economic, social and environmental systems under the overall level of Wanjiang urban belt, the degree of influence of the development of each subsystem on the coordinated development is ranked: environmental subsystem  economic subsystem  social subsystem. In the environmental subsystem, environmental state = environmental pressure  environmental response, and surface water quality, per capita industrial solid waste production, green coverage of constructed areas are three most influential social indicators. In the economic subsystem, economic structure  developing quality  economic benefits, proportion of foreign direct investment in GDP, the proportion of R & D expenditure in GDP, the proportion of tertiary industry in GDP are three most influential economic indicators. In the social subsystem, public service  living standards  quality of life, and urbanization rate of permanent population, per capita road mileage, and the number of hospital beds per 10,000 people are three most influential social indicators.