Abstract: Studied the reliable H∞ control design of dynamic output feedback control for linear systems on the basis of the linear matrix inequality (LMI). During the design a continuous fault model that is more practical than discrete fault one is developed. The reliable control systems designed can ensure the asymptotic stability and H∞ performance of an actuator in operation whether a fault happens or not. Under the conditions that an H∞ performance bound is given when a fault happens, the H∞ performance of a system is optimized in case no fault happens. A numerical example is also given to illustrate the design procedure and its effectiveness.