The utility model discloses a direct tail gas discharge type unmanned aerial vehicle. The direct tail gas discharge type unmanned aerial vehicle comprises a fuselage, a rotor wing main shaft and a rotor holder pin shaft. The unmanned aerial vehicle further comprises an engine and an air cleaner. The engine is fixed into the fuselage and comprises at least one cylinder, a cylinder body and an air inlet valve, wherein an exhaust opening is formed in one side face of each cylinder, the cylinder body is detachably connected with the cylinders, and the air inlet valve is detachably connected with the cylinder body. The air cleaner is fixed to the bottom of the machine body and comprises a ventilation groove, a filter screen and a fairing, wherein the ventilation groove is fixed to the bottom of the fuselage, the filter screen is fixed into the ventilation groove, one end of the fairing is detachably connected with the air inlet valve, the other end of the fairing is fixedly connected with the ventilation groove, and therefore air can sequentially pass through the filter screen and the fairing to flow into the air inlet valve.