Abstract: Complex engine control strategy,including constant fuel supply,constant speed control and forward-feed compensation control rule was proposed for an unmanned helicopter engine.Fuzzy adaptive PID controller was built in a flight control computer.Adopting fuzzy rule and fuzzy inference were used to adjust PID parameters on-line and thus to make engine start smoothly and keep constant rotor speed at all power settings.It is proved by hardware-in-loop simulation,engine ground test,tethered test and flight test that the engine control strategy designed has quick transient response and it is robust to disturbance such as overall pitch variation.The results show that the main rotor yields best aerodynamic efficiency at all flight status,and thus the flight performance of the unmanned helicopter can be improved.