On basis of a baseline survey to the natural environment condition, social economy situation, pollution source distribution situation and aquatic ecological environment situation in Liangzi Lake Basin, the author of this paper analyzed the water environmental quality and biodiversity of Liangzi Lake. According to the problems that the water quality of Liangzi Lake was eutrophic and the biodiversity was decreasing, some countermeasures and suggestion were put forward: strengthen the propaganda of Liangzi Lake protection, improve the sewage discharge standard rate, establish a long-term mechanism of environmental protection in Liangzi Lake.