The invention relates to the technical field of unmanned helicopters, in particular to an electronic fuel injection engine of an unmanned helicopter. The electronic fuel injection engine of the unmanned helicopter comprises a generator, a starting gear disc, an engine cylinder, a spark plug, an electronic injection system, an output shaft, a heat dissipating fan and a heat dissipating water tank, wherein the starting gear disc is arranged under the generator; the spark plug is arranged on the side surface of the engine cylinder; the electronic injection system comprises an oil supply system, an air filter system and an electronic control unit (ECU); the electronic control unit (ECU) is arranged at the starting gear disc; a connector of an oil tank is connected with the engine cylinder; the output shaft is arranged under the engine cylinder and is connected with the heat dissipating fan; and the heat dissipating water tank is arranged under the heat dissipating fan. Compared with a traditional mechanical carburetor, the electronic fuel injection engine of the unmanned helicopter provided by the invention has the advantages that the power is higher, the emission is lower, the environmental suitability is better, and endurance of the unmanned helicopter system is longer.