Temporal and spatial characteristics analysis of water quality and pollution source identification in Li-Xia River watershed are the important aspects for water quality management and pollution control. Ten water quality indexes from 37 monitoring sections in the watershed during 2011 was collected. This paper analyzed the temporal and spatial distribution feature of main contaminations and pollution source by use of the methods of single factor pollution index assessment, comprehensive water quality identification index and principal component analysis and GIS software. The results showed that the comprehensive water quality in non-flood period is better than that in flood,while water quality in 40.5% of the monitoring sites in non-floodperiod is classified as grade Ⅲ,and that in 70.3% of the sites in flood period is classified as grade Ⅲ; the water quality in northeast is worse than that in southwest,but the water quality in main irrigation canal is the best due to the impact of water quality in Hongze lake;the main pollutants are CODMn, TP, CODCr, NH+4-N, BOD5 in flood period, while the main pollutants are TP, CODCr, NH+4-N, BOD5 ,Mn in non-flood period from domestic and industrial wastewater.