Abstract: Uncertainties such as model parameter variation and exogenous disturbance, which simultaneously exist in an aircraft during flight, will lead to instability and performance degradation of the system. In this paper, an LMI-based H₂/H_∞ control method is used to design a robust state feedback controller for such aircraft plant. Numerical results shown that the colsedloop system has both the satisfactory robust stability and the excellent ability of rejecting exogenous noise.