Abstract: Severe vibration of large-scale radial steel gates can induce dynamic instability damage. In order to investigate dynamic characteristics of a new type of radial gates, the reversed radial cavity gate, a new FORTRAN subroutine was developed in this study. Using the two development functions of the finite element software ABAQUS, the data of the dispersion flow pressure fluctuation measured by the model tests are transformed into hydrodynamic loads upon the gate. Based on the random vibration analysis method, the dynamic numerical simulation of the cavity gate is carried out. The complete analysis method consists of the following steps: ① estimate the frequency and vibration mode for the gate under different working conditions; ② analyze the spectrum for the time series of fluctuating pressure of the water flow; ③quantify the response of the gate to the random vibration under different working conditions; ④develop the subroutine to analyze the extreme values of displacement and stress for the gate. The analysis results show that the local stress of the gate is larger than the allowable stress of the structure. This requires modifications and optimizations of the gate structure, otherwise the local strength of the structure cannot meet the stability requirements. This numerical analysis method has a potential to be used for improving the dynamic stability of the hydraulic radial gates.