Aiming at the uncertainties of an unmanned helicopter system and its controller,based on the idea of eigenvalue perturbation,a normalized non-fragile controller is designed to ensure the system′s good robustness and flight performance.Firstly,the T-S fuzzy model of the nonlinear attitude dynamics for an unmanned helicopter is established.Secondly,based on the idea of eigenvalue perturbation,a normalized design is carried out for the nominal part of the system to make the eigenvalue perturbation of the nominal part insensitive to the system uncertainties.Thirdly,considering the system uncertainties and the additive perturbation of the controller gain,a fuzzy non-fragile controller is designed for the uncertain part.Based on Lyapunov theory,the stability of the closed-loop system is analyzed,and the controller parameters are solved by Linear Matrix Inequality (LMI) method.Finally,the simulation results show that the designed controller has good robustness.