Abstract: The chaotic behavior of a liquid level control system is analyzed in this paper.The first order nonlinear discrete system can display chaos due to sampling.Furthermore, bifurcation diagrams versus two parameters are shown. Some researchers proposed optimal control based on local linearization, which causes some problems,for example the control objective is confined to the fixed point of the system and the control method is effective near the fixed point. It is suggested in this paper that the optimal control method based on feedback linearization is used to control chaotic behavior in order to solve problems caused by local linearization. The feedback technology is used to linearize the nonlinear model of the liquid level control system, and then the optimal method is used to control the linearized system. The control objective is not confined to the fixed point and that the method is effective globally.Moreover, the method can be easily implemented. Simulation results show the effectiveness and feasibility of the method.