As a kind of uncertain system， the speed limit system should be robust and robust steady， which means the internal stability of each system can be guaranteed.Aiming at this problem， by using the methods of macroscopic traffic flow model is established based on nonlinear state equation， the model is stable in the case of a certain disturbance.The follow-ing steps of analysis and calculation are taken：①Based on the uncertain affine nonlinear sys-tem， the nominal state space model is searched； ②Application of state feedback linearization method， the nonlinear system of strict linear nominal； ③by considering affine nonlinear systems with uncertainties， the feedback linearization system can use the addition of linear uncertain systems or multiplicative uncertainty to describe system； ④According to the feed-back linearization system， design of linear robust controller using DK iterative method or pK iterative method； ⑤the linear robust controller back to affine nonlinear system， so as to obtain the nonlinear robust controller.