The starting principles of bottom mud in Lake Taihu were simulated in the laboratory in an annular tank;and the different stages of bottom mud movement were analyzed in this paper.The velocity of flow was basically uniformity in this annular tank, the rotation rate of tank and velocity of flow can be converted accurately, the law of sediment suspension and releasing were simulated by deferent disturbance forces.The sediments from Lake Taihu were used in this experiment, the relational expression between the release rate of TN, TP and water velocity was calculated on the basis of the relationship between the concentration of TN, TP and water velocity.The calculated result was applied in the mathematical model of water flow and water quality in Lake Taihu, and a satisfactory result was obtained.