This paper addresses the robust stability test problem for discrete time-delay systems subjected to uncertainties. By using Lyapunov stability theorem associated with solution bound of Lyapunov equation, a concise criterion is presented to guarantee the robust stability of the time-delay systems. Then, this approach is applied to discuss the same problem for time-delay systems with nonlinear uncertainties. A robust stability condition is also obtained. The feature of these present criteria is that they are independent of any Lyapunov equation although the Lyapunov approach is adopted.