This article studies the aeroacoustics characteristics of typical cavity structures in aircraft under seal failure conditions through simulation analysis and wind tunnel testing. A wind tunnel test was designed to investigate the local details of typical aircraft cavity structures at the inlet of the airflow, and the effects of different velocities and opening lengths on aeroacoustics characteristics in typical cavities were studied. Within a certain speed range, the sound pressure level at each point inside the cavity is mainly dominated by the sound mode of the cavity, and the peak frequency does not change significantly with the variation of the incoming flow velocity. When the opening size is large, the fluid dynamics mode couples with the first-order cavity acoustic mode, producing strong unimodal noise. However, as the size of the cavity opening gradually decreases, strong unimodal noise is also generated near the second-order acoustic resonance frequency of the cavity. The research results indicate that the length of the opening flow direction has a significant impact on the flow characteristics of the cavity. Conducting structural frequency avoidance design on typical cavity structures on aircraft to avoid acoustic resonance frequencies of cavities can effectively reduce noise excitation loads and thus reduce structural vibration damage.