Eutrophication status of Yuqiao Reservoir and the main influence factors were analyzed in order to strengthen the urban water supply safety and ensure the drinking water quality. Based on the method of principal component analysis with water quality monitoring data of Yuqiao reservior, the indicators that influence eutrophication such as chlorophyll a, total nitrogen, total phosphorus, ammonia nitrogen, potassium permanganate index were analyzed to reduce dimensions from 10to 4and the former 4principal components can explain 73.6% of the whole data. On the basis of main components screening the factor analysis were further carried out, and the space distribution of every factor was also described in order to provide the theory basis for Yuqiao Reservoir ecological management. Results show that the water temperature, PH, COD and dissolved oxygen are the main driving factors which influence reservoir eutrophication, and the principal components have the highest value in the central area of the reservoir.