Abstract: To investigate the influence of boundary conditions on the aerodynamic noise of three-dimensional unsteady flow around a single circular cylinder, numerical simulations are conducted to investigate the radiated characteristics of near-field and far-field aerodynamic noise from a single circular cylinder under four different sets of boundary conditions based on the large eddy simulation (LES) and Ffowcs Williams Hawkings (FW-H) acoustic analogy. Comparison between the numerical simulation results of benchmark cases and the experimental results in the literature indicates that setting the boundary conditions of the inflow face, outflow face, and spanwise sides as free flow, while the vertical top and bottom surfaces as fully developed periodic boundaries, allows for a better prediction of the Sound Pressure Level (SPL) frequency and its corresponding peaks, showing good agreement with the experimental results. Further analysis reveals that, compared to the other three cases with different boundary conditions, setting the inflow face, outflow face, and spanwise sides of the computational domain as free flow boundaries, where there are no sound reflections along the flow and spanwise directions, is more suitable for numerical simulations of this type of aerodynamic noise. The conclusion of this study provides a feasible boundary condition setting for the numerical simulation of aerodynamic noise from cylindrical structures, multiple cylinders, or even more complex configurations.