The organic matter(OM) content, compositions and fractions of shallow lake sediments were studied by chemical method from in the middle and lower reaches of Yangtze River.The results showed that the OM content varied greatly from 0.98% to 11.0%, higher in the heavily polluted sediments than those in the light polluted ones.The distributions of OM content were closely related to lake pollution levels and human activity intensity.HA content was 1.03-6.73g/kg, and FA content is higher than the HA, from 2.73 to 9.77g/kg.Humin was the main fractions of humus, varing firom 5.89 to 55.57g/kg.PQ(HA/(FA+HA)) ratio varied from 23.04% to 50.56%, and the mean content of PQ was 32.72%.PQ content were higher in the heavily polluted sediments than those in the light polluted ones, which indicated that there was a higher degree of humification in heavy polluted sediments.Combination of three kinds of humus content in the form of tightly bound humus content was the highest, and content was 3.21-47.76g/kg;followed by loosely combined humus content between 0.86-6.92g/kg.The stable combined humus were the lowest, the content varied from 0.72 to 3.89 g/kg.The looee/tight ration in the sediments were also negatively correlated with OM, TP and TN, which showed that heavily polluted shallow lakes had higher humification and humus accumulation.So humus should be paid more attention to the carbon cycling and eutrophication control in lakes.