Abstract:3-D numerical simulation was carried out for the water flow during the radial gate opening by using dynamic mesh model and VOF method. Three different opening velocities were choosed for obtaining detailed characteristics;the space-time change laws of pressure, velocity and other hydraulic parameters of radial gate, flaring gate pier and stilling pool were described; the moment and location of cavitations erosion that occurred easily in the process were also obtained, and disadvantages were pointed out under the high opening velocity. Moreover some results of the calculations were compared with the model test data and good agreement was found. The results indicated that this method can be used to provide references for determining the reasonable operation mode of radial gate and shape optimization of practical project.