Abstract: The propagation characteristics of the blade–vortex interaction (BVI) noise were tested in the FL–10 wind tunnel of AVIC Aerodynamics Research Institute. The aerodynamic noise of climb, level flight and descent at medium forward speed was measured on a 40% scale model of BO−105 main rotor. Firstly, the “Heyson” wall interference correction method was used to determine the descent angle of the rotor in the wind tunnel, and the complete noise radiation field under the rotor tip–path–plane was obtained through the movement of the measurement array in the airflow. Furthermore, the BVI noise characteristics of the rotor under different flight condition were studied, and the sound pressure time history, spectrum and sound pressure level contour were given. The results indicate that the BVI phenomena occur on both the advancing and retreating side under the descent flight condition. The noise has strong directivity, and radiates toward upstream under the rotor disk toward the advancing side and the downstream on the retreating side.