Water eutrophication is one of the most serious types of water pollution in reservoirs and lakes.In order to understand the level of organic pollution in reservoir sediments in Jiangxi province，the author measured the content of TP，TN，and TOC in the sediments of 15 medium-sized reservoirs in Jiangxi province，analyzed and studied their distribution characteristics and sources，and used the organic index method for comprehensive evaluation.The results showed：Typical reservoir sediments TP and TN in Jiangxi province are generally slightly polluted；in terms of spatial distribution，the overall changes in TN and TOC contents are not obvious，and the contents of TP，TN and TOC in the sediments of reservoirs in the upper and middle reaches of Ganjiang river are generally low.The TOC/TN ratio indicates that aquatic animals and terrestrial animals are the main sources of organic matter in sediments.Pollution evaluation results show that the average organic index IO is 0.13，and the overall level is clean （leve l II）；while the average organic nitrogen WON is 0.09，ranked as Leve l III（relatively clean）.