Abstract: Changes and spatial correlations of the water quality of 7 rivers of Hongze Lake were studied based on bi-monthly monitoring data from 15 sites distributed in the 7 rivers in Sihong county from 1996 to 2008. The rivers in the study area could be divided into 3 classes; the eastern rivers were mainly for irrigation and flood drainage, the western rivers mainly acted as the channel for the upper rivers to the Hongze Lake, while the central rivers went through the urban area of Sihong county. The results showed that:(1)Water quality of the western rivers was significantly deteriorated, and that in the central and eastern rivers was slightly deteriorated.(2)The main pollutants in the study area were organic pollutants, the main pollutants in the central rivers across the urban area were TN and ammonia nitrogen; the main pollutants of the western rivers were petroleum and COD, while petroleum and TN were the main pollutants of the eastern rivers. The pollution load had regional differentiation.(3)BOD₅, COD, volatile phenols, mercury and petroleum showed similar dynamics in all three areas, while ammonia nitrogen and TN showed diverse dynamics comparatively.