Abstract: Water transparency and other physicochemical factors such as total phosphorus, total nitrogen, suspended solids, chlorophyll a,water temperature and BOD5 were analyzed based on seasonal monitoring in Waihai area of Lake Dianchi in 2019. The results indicated that the water transparency in Waihai area of Lake Dianchi ranged from 0.20 meter to 0.53 meter with a mean value of 0.37 meter. Water transparency in dry season(winter and spring) was significantly higher than rainy season(summer and autumn). The correlation analysis and multiple stepwise regression analysis results showed that total phosphorus and suspended solids are two significant factors that affected the transparency. The main factor affecting the transparency is total phosphorus in dry season, while it becomes total nitrogen in rainy season.