Abstract: According to the reality of water environmental quality in rural areas of China, this paper puts forward the concept and the building principles of early-warning system for water environmental quality in rural areas. Meanwhile, the frame system for the early-warning system was designed for three layers including basic data layer, professional service layer and decision application layer, and also the function of the system was described. The monitoring network and distribution for water environmental quality were further proposed, and the index systems for early-warning were set up. It was proved that the early-warning system was helpful for the improvement of the water environment quality and the national water resource security.