The city of Shiyan in Hubei Province is the largest city in the source of the South to North Water Diversion Project in China. The water of this project will be sent to Beijing, so water quality is very important. In the city district there is a 100 km river along a cross-strait with high-rise buildings, dense population, and converged sewage straight flow to the river. In our paper, the design of the “Ming change dark” river closure project can fundamentally solve the city environmental pollution problems, improve the source water quality without any menace from the “rears,” and make Shiyan's green economy grow rapidly. On the other hand, this “city agriculture” new thinking will completely change the serious situation of arable land area, which is decreasing year by year in the world. The exploitation of the riverway is an opportunity for Shiyan. It is a green project meaningful to the city’s continuing development.