Abstract: In view of the aerodynamic noise problem of a flue duct after the induced draft fan of a power plant, a numerical simulation was conducted based on Fluent, and the method combining large-eddy simulation and FW-H equation was adopted to analyze the aerodynamic noise at the monitoring points outside the pipe, and then the different optimization schemes were achieved. Results show that when increasing the cross-sectional area of the pipe, a high turbulent kinetic energy area will appear near the wall after the flue gas enters the flue. And the installation of deflectors can improve the uniformity of flow distribution and reduce the turbulent kinetic energy at the bend. When the two assemblies installed in the first and second bends both contain two deflectors, the noise reduction is relatively effective. Compared with the original flue containing eight and six deflectors, the average total sound pressure level of aerodynamic noise is reduced by 4.8%.