Based on Lyapunov-Krasovskii functional approach, an analysis has been made of the robust stability of the power system with uncertain time-delay. By constructing an appropriate Lyapunov-Krasovskii functional and adopting the approach of free matrix integral inequality to deal with the integral terms yielded in functional derivatives, a new robust stability criterion has thus been established for uncertain time-delay systems. A comparison between the simulation results of numerical examples and those of other recorded statistics verify the effectiveness and advantages of the proposed method.