This paper researches the design methodology for multivariable robust controller of aero-engine.A small-divergence state space model for a given jet aero-engine has been established with the difference method.The Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) method has been used to design a BIBO robust controller for the engine.The functions of the controller such as command following

decoupling and disturbance rejection have been considered.It is demonstrated that the LQG/LTR controller has excellent robustness for the uncertainty of the plant model.