A method of uncertainty modeling is proposed for the flight control system with wide operation range. The model built according to this method contains two parts: one is a polynomial matrix obtained via least square fitting, and the other is the fitting error. The polynomial matrix is related to the parameters and reflects the time-varying characteristic. The fitting error is considered as norm-bounded uncertainties and reflects the uncertain and nonlinear characteristics of the system. And as an example, a model is built for a certain flight control system.