Abstract: The paper is concerned with discrete-time optimal control method for linear systems with time-delay. Using zero-order holder, the continuous-time differential equation with time delay can be transformed into standard discrete-time form without time delay. The controller is designed considering two cases that the time delay is integer and non-integer times of the sampling period, respectively. Since the optimal controller is obtained directly from the differential equation with time-delay, the proposed control method is able to guarantee stability of the controlled structures. Simulation results demonstrate that the continuous time performance index is superior to that of discrete-time and the present control method ensures the stability of the controlled structures as well as the desired reduction in the maximum responses.