This paper addresses a new decentralized robust control design for load-frequency control (LFC) in multi-area power systems. The LFC problem is considered as a multi-objective problem and formulated via a mixed H2/H∞ control technique, then it is easily carried out to synthesis the desired robust controllers by solving standard linear matrix inequalities (LMI). A three-area power system example with a wide range of load changes is given to illustrate the proposed approach. The results are compared with pure H∞ method. It is shown that the designed controllers maintain the robust performance, minimize the effect of disturbances and specified uncertainties, effectively.