Abstract: Modern new coal chemical industry is an important direction for the clean utilization of coal. It belongs to technology, capital, and resource-intensive industries and it is faced with factors such as technological maturity, investment scale, carbon dioxide emissions, and environment. In order to evaluate the benefits of modern coal chemical projects based on environmental constraints, this paper carried out a screening and identification study of economic risk types, impact factors and degree of impact of economic risks of coal chemical projects based on environmental constraints, especially for potential and possible water pollution，atmospheric pollution, solid waste pollution, carbon emissions and other environmental risks, quantified the environmental losses such as land and atmosphere that may be caused by pollutant and carbon dioxide emissions. According to the characteristics of the coal chemical industry, especially the characteristics of large environmental risks and large water consumption, the cost-benefit analysis theory was used to construct a modern coal chemical project benefit evaluation method based on environmental constraints, determine the cost and benefit categories, and establish the modern coal chemical project benefit evaluation method and model based on environmental constraints.