The invention specifically relates to an unmanned aerial vehicle used for pesticide spraying. The unmanned aerial vehicle includes an unmanned aerial vehicle body, a support flat plate, a pesticide liquid box and a pesticide spraying device; the support flat plate is fixedly connected with the lower portion of the unmanned aerial vehicle body, and a working chamber is connected with the bottom surface of the support flat plate; the pesticide spraying device includes a pressurization pump, a liquid feeding bottle, a connecting pipe and a spray rod; the spray rod is fixed on the outer side of the bottom surface of the working chamber, and the spray rod is uniformly provided with several nozzles, the spray rod is of an extendable structure, the end portions of the two sides of the spray rod are provided with internal threaded holes, plugs and extension tubes, the plugs and the extension tubes are matched with internal threads and both provided with external threads matched with the internal threads, and each extension tube is uniformly provided with several nozzles. According to the unmanned aerial vehicle, the spray rod is of the extendable structure, when in transportation, the space occupied by the unmanned aerial vehicle in the width direction can be reduced, the unmanned aerial vehicle is convenient to transport, when the unmanned aerial vehicle is in use, the spray rod can extend, since the spray rod is uniformly provided with the nozzles, the spraying area is increased, and the work efficiency is thus greatly improved.