In order to explore the effect of bermuda grass root exudates on migration and bioavailability of Pb in the fluctuation zone, low molecular weight organic acids secreted by bermuda grass roots of the dominant plants in the fluctuating zone of Three Gorges Reservoir area were selected, and the effects of root exudates on the total amount of Pb in contaminated soil and overlying water and the occurrence forms of Pb in soil were investigated in the dry and wet alternate environment through simulation tests. The results showed that in the wet and dry alternate environment, the Pb content in the topsoil decreased, the content of Pb in the bottom soil increased. After two times of wet and dry alternating, the Pb content in topsoil of the different treatments followed the order of mixed acid > citric acid ≈ acetic acid > malonic acid > control, the Pb content in the bottom soil was sorted as mixed acid > citric acid ≈ acetic acid > malonic acid > control. Carbonate-bound Pb and iron-manganese oxidized Pb in surface soil were the main reasons for the decrease of total Pb content, maximum reduction rates was 24.89% and 19.04% respectively. However, in the treatments added low molecular weight organic acids, the contents of Fe-Mn oxidized Pb and organic bound Pb in surface soil were higher than those in the control, while the exchangeable Pb content was lower than that of the control. Moreover, organic acids promoted the increase of contents of Pb in the carbonate bound state and Fe-Mn oxidation state in the bottom soil. During the two flooding process, the content of Pb in overlying water both increased first and then decreased, low molecular weight organic acids inhibited the release of Pb from soil to overlying water. In general, in the wet and dry alternate environment, the root exudates of bermuda grass reduced the environmental risk of Pb in topsoil.