Abstract: In order to improve the airborne magnetic detection accuracy of the UAV, in this paper, a magnetic field measurement system is set up by using the DJI six-rotor drone as the flight platform, with a three-axis magnetic fluxgate sensor and the corresponding data acquisition system,. The distributions of the background magnetic field around the six rotor drone are measured and analyzed in detail, and then the installation position of the non-magnetic extension rod is optimized. The errors of the three-axis magnetic fluxgate sensor are corrected by the comprehensive coefficient method. The field flight test is carried out to verify the overall performance of the magnetic measurement system, and the results show that the system can fly continuously for 15 minutes, to complete the low-altitude magnetic field detection and the magnetic moment calculation effectively, and the system enjoys high flight stability performance. The further direction of the technical improvement is proposed. This study provides a reference for the UAV magnetic exploration technology and the related engineering applications.