In this study, an airborne radioactivity survey (ARS) system based on an unmanned helicopter platform was designed to satisfy the requirements of geological exploration and environmental radiation monitoring under complex environmental conditions. The system is composed of an unmanned aerial vehicle platform, airborne equipment, and a ground control station, with both NaI(Tl) and CeBr3 crystals as detectors to meet the energy resolution and detection efficiency requirements of airborne radioactivity measurement. The designed ARS system is stable and reliable through the field flight test, and the measurement results are consistent with the existing data and can be widely used in fields such as large-scale uranium resource exploration, nuclear accident emergency monitoring, and environmental radiation investigation.