In order to reject the effects of disturbances on path tracking accuracy of AGVs(Autonomous Guided Vehicles), an observer-based H_infinity preview controller is proposed in this paper. Firstly, the path tracking error model of AGV is converted into a linear variable parameter (LPV) model. Secondly, a preview model of the path curvature is established, and an augmented system is constructed by combining the path tracking model and the preview model. Considering the influence of sensor measurement noises on the path tracking accuracy, an observer-based H_infinity state-feedback controller is designed, the design conditions of which are converted into solving a set of linear matrix inequalities (LMIs). Finally, simulation results through utilizing Simulink/CarSim show that, the H_infinity preview controller proposed in this paper receives better path tracking results compared with existing methods, where measurement noises are attenuated effectively.