The utility model relates to an insulator detecting device by using a multi-rotor unmanned aerial vehicle. The device comprises a multi-rotor unmanned aerial vehicle, wherein a flight control system airborne computer thereon is connected with a positioning device, an unmanned aerial vehicle steering engine controller, a height measuring device, a speed measuring device, a high-definition camera, an unmanned aerial vehicle PCM remote-controlled receiver, an airborne wireless communication unit and a lifting device; the lifting device drives a detecting lower electrode to move, and the airborne wireless communication unit communicates with a ground station; and the unmanned aerial vehicle steering engine controller controls a servo steering engine, the servo steering engine controls a multi-rotor module, a detecting upper electrode and the detecting lower electrode are respectively connected with respective voltage sensor, and the two voltage sensors are connected with an A/D conversion unit, a DSP processing unit, and the flight control system airborne computer. The insulator detecting device can know and master the running conditions of the line insulators timely, can avoid the danger that is caused when the detecting personnel climb to carry out short-distance live operation, and can improve the detection efficiency.