In this paper we study the behavior of a semi-active suspension witch external vibrations. The mathematical model is proposed coupled to a magneto rheological (MR) damper. The goal of this work is stabilize of the external vibration that affect the comfort and durability an vehicle, to control these vibrations we propose the combination of two control strategies, the optimal linear control and the magneto rheological (MR) damper. The optimal linear control is a linear feedback control problem for nonlinear systems, under the optimal control theory viewpoint We also developed the optimal linear control design with the scope in to reducing the external vibrating of the nonlinear systems in a stable point. Here, we discuss the conditions that allow us to the linear optimal control for this kind of non-linear system.UNESP Univ Estadual Paulista, Fac Engn, Dept Math, BR-15385000 Ilha Solteira, SP, BrazilUNESP Univ Estadual Paulista, Fac Engn, Dept Math, BR-15385000 Ilha Solteira, SP, Brazil