The invention discloses an unmanned plane mounted nuclear radiation detection device. The device comprises an unmanned aircraft, an aerial photography camera, a nuclear radiation sensor, a microcontroller, a wireless communication device, and a solar cell panel. The device can enter a high radiation region, which a ground person cannot enter, for detection, quickly detects the type of radionuclides and the dosage of nuclear radiation in the region, and guarantees the personal safety of a technician. Meanwhile, the device also can carry out the aerial photography of the resources of a complex terrain region and the environment radioactivity. Through an airborne solar cell panel power supply system, the device can work for a long time without worrying the duration. The ground person can freely control an unmanned plane to detect a target region according to a picture taken by the aerial photography camera.