Abstract: This paper studies the optimal H_∞ control problem for a class of networked control system(NCS) with uncertain time-delay.For the networked control systems with clock-driven sensors and event-driven actuators and controllers,supposing that the time-delay is uncertain and not more than one sampling period and the external disturbance is limited,the sufficient and necessary condition of the existence of suboptimal H_∞ control law for dynamical output feedback is derived by using Lyapunov theory and linear matrix inequality formulation,and optimal H_∞ control law design methods for dynamical output feedback are presented.A numerical simulation example with Matlab shows that the analysis method and the results are valid and feasible.