Abstract: Flow past a weapon bay has a number of complex flow characteristics, such as the boundary layer separation, shear layer instabilities, acoustic noise, which may cause damage to the internal equipment or structure of the weapon bay itself. In this study, a complex weapon bay was developed to incorporate more realistic weapon bay features, and the unsteady flow characteristics inside the weapon bay were obtained using a high-precision numerical method. The noise generation mechanism was unveiled, based on which three types of flow control schemes, i.e. the leading-edge spoiler, the still-pipe, and the leading-edge air blowing, were proposed. Influence of the weapon-bay door opening angle and the embedded weapon on the noise level was systematically investigated using high-speed wind tunnel tests, and the noise reduction effects of different control devices were analyzed. The results show that, flow inside the weapon bay is dominated by small scale turbulent structures. The overall sound pressure level (OASPL) of the front cabin is relatively high when the door opening is small, and that of the rear cabin increases as the opening degree increases. After the door is opened to a certain extent, the OASPL distribution in the cabin remains the same. Embedding weapons lowers the OASPL in the weapon bay by weakening the slap intensity of the flow on each wall. All three control methods show significant reduction of OASPL by lifting up the shear layer and reducing the injected energy into the weapon bay. Based on the present study, the leading-edge spoiler is most effective in noise reduction, which can reduce the amplitude of OASPL by more than 5 dB.