With the reform and opening to the outer world, Datian has become a new industrial county from an agricultural one. With the development of industry, most of the waste water from the factories, families, farms is poured into the river without being disposed. The water in the county is being polluted. Mining in large scale and the cutting down of forests has caused soil erosion and destruction of the water system. In order to harmonize the economic development and the environment, this essay will make comments on the destruction of the water system in the county of Datian caused by the pollution and soil erosion, and put forth some protection measures and recovering plans.