Abstract:The West Lake area of Hengshui Lake is an important ecosystem service supply area, part of the soil would be flooded in the process of ecological water replenishment and returning farmland to the lake. This paper scientifically evaluated the ecological risk of soils in the West Lake area from the following three aspects:the distribution characteristics of soil heavy metals, the assessment of ecological risk, and the risk estimation of flood release flux, in which 46 quadrats of 9 sections were arranged, 0-60 cm soils were sampled, and 7 types of controlled heavy metals were determined, the spatial distribution characteristics of heavy metals and ecological risk levels were assessed using the methods of geo-accumulation index and potential ecological hazard index, the risk of heavy metal release of flooded soils were evaluated by indoor simulation method. The results showed that the average contents of Zn and Cd in the soil of the West Lake area was significantly higher than the background values in Hebei Province, Cd accumulation was relatively obvious, with 97.83% of the area above the moderate pollution level. The contents of all heavy metals were higher in the south and north but lower in the middle, the soil was at a low risk level as a whole. The contribution rates of heavy metals to ecological risk were as follows:Cd>As>Pb>Cu>Ni>Cr>Zn, 37.71% of the ecological risk was from Cd, followed by As (18.81%) and Pb (4.94%). The release characteristics of heavy metals in flooded soil varied significantly with land use types, in which the vegetable fields had the highest release flux, followed by the orchards, while the wheat fields were the lowest. The accumulation of organic matter caused by different land use types may be the main reason for the difference in heavy metal release flux in soils. The surrounding area of Hengshui Lake is dominated by calcareous soil (soil surface leaching solution pH≈9; Ca2+ content was 1.135-1.143 mg/g), these heavy metals mainly occurred in carbonate binding state are relatively stable, the leaching concentrations of all heavy metals in water soluble state did not exceed the standard after being flooded. Thus, the overall risk of water ecological security is low after returning farmland to lake in the West Lake area of Hengshui Lake.