The serious aerodynamic noise is caused in the downstream of control valve by high pressure difference. Severe aerodynamic noise will affect worker safety and production safety. Throttling orifice plate located in control valve downstream is one of the most important devices for reducing aerodynamic noise under high pressure difference. Therefore, studying the effect of throttling orifice plate structure parameters on flow characteristics and aerodynamic noise is of great significance. Based on method of computational fluid dynamics, the inclination angle of conical throttling orifice plate is studied as the research variables. The time-average values of the flow field, pressure and velocity are obtained and evaluated through steady-state RANS. Flow rate is evaluated under condition that the throttling area of the plate remains unchanged. Based on the results of steady-state simulation, the aerodynamic acoustic power level in the whole flow field is obtained through the broadband noise source model. Finally, the influence of the plate inclination angle on the aerodynamic noise is comprehensively evaluated. It is concluded that the downward setting orifice plate (45°) is the best among the all orifice plates. The work has a certain reference value for researching the design of throttling orifice plate and improving aerodynamic noise in downstream of high pressure valve.