A robust controller, based on the Riccati-equation approach, is proposed for power system load-frequency control. Only the bounds of the system parameters are required to design the robust load-frequency controller. The proposed robust controller is simple, effective and can ensure that the overall system is asymptotically stable for all admissable uncertainties. Simulation results show that, for the example system, the proposed robust load-frequency controller can achieve good performance even in the presence of generation rate constraint.