The eight water systems in Zhejiang Province are the main water systems that support the economic development and ensure the drinking water sources.Currently the eight water systems are polluted to various extents.The main socioeconomic factors that affect the water systems pollution could be divided into five types by factor analysis,namel,regional economic development factor,agriculture development factor,agriculture and forestry services factor,fishery development factor,and population density factor.Yongjiang river ranked first based on the total socioeconomic scores among the eight water systems,followed by Tiaoxi river,Cao' a river,Aojiang river,Jiaojiang river,Qiantang river,Oujiang river,and Feiyunjiang river.Water was polluted at the least when the scores of all the five factors are between-1 and 0.On the other hand,the total score being above 3 or below-3 indicated that the water pollution degree was the lowest,with sort ofⅠ,Ⅱand Ⅲ water accounting for more than 90%.Water pollution is related to the level of economic development,but in a large degree,it is the result of the interaction between economic development and other factors,and is more closed to the balanced development of the five socioeconomic factors.The water pollution degree was positively related with the unit area of first output value in the region where agriculture and forestry are not prominent.