Abstract: Based on a 3-D fluid-structure interaction dynamics model and direct coupling solving method, the nonlinear dynamic response characteristics, such as variable flow rate, pressure difference and valve opening, of a conical orifice valve are numerically simulated to show its whole working process of opening and closing under inlet fluid velocity pulse excitation. Especially, the high-frequency fluctuation characteristics of valve opening are investigated in details. The wavelet analysis method for short unstationary process data is employed to analyze the time-frequency spectrum of the valve opening response. Practical verification of the solution algorithms is performed using different time-integration methods and time steps. Then, a series of numerical experiments are conducted to compare the effects of each change of several system parameters, such as valve core mass, spring parameters and hydraulic oil parameters, and excitation parameters, such as inlet fluid velocity amplitude and ulse width. The numerical experiment results show that the different fluid integration algorithms influence the solution results quite much; the influences of change in valve core mass or fluid compressibility on the valve opening oscillation frequency are significant; oil viscosity change leads to oscillation phase difference; different spring stiffnesses and preloads change the maximum valve opening; the initial collisions between valve core and seat result in increase of the valve opening oscillation frequency.