Abstract: A robust speed control of a gasoline engine for a mini unmanned helicopter is presented. A set of linear interval plants used for controller design is developed from step responses. According to the nonlinear nature of the engine and the induction-to-power delay of the manifold filling dynamics, a robust feedback control approach is adopted to realize the speed control of engine based on quantitative feedback theory (QFT), which can provide reference speed tracking despite the presence of torque load disturbances. The off-line simulations show that the proposed engine control strategy has quick transient response and is robust to disturbances such as overall pitch variation.