Abstract: Using a three-dimensional RNG k-ε turbulence model and the method of the volume rate(VOF) to track free water surface,the hydraulic jump characteristics of a plunge pool behind the steep slope with the same slope angle are simulated under 4 different working conditions in this study.By comparing the simulated results with the model test results,we find that the feature of water surface profile,velocity and length of the hydraulic jump agree well with each other,and the length of submerged hydraulic jump is greater than that of free critical hydraulic jump in the plunge pool behind the steep slope.The numerical calculation and the test results indicate that the length of the hydraulic jump in the plunge pool behind the steep slope can not be calculated by a formula used in flat bottom rectangular hydraulic jump,and the influence of submergence degree must be considered to avoid the designing deficiency of the plunge pool behind the steep slope.