In this research a Multi-objective Imperialist Competitive Algorithm (MOICA) is applied for Environmental/Economic/Reliability Power Dispatch (EERD) problem. For the EERD problems treats economic, emission and reliability impact as competing objectives. There are lots of indexes used for the evaluation of electric power generation units. All the mentioned problem has been optimized by proposed ICA technique. At last, the feasibility of the proposed method is demonstrated from 8 unit systems, and the test results are compared with those obtained by Simulate Anneal (SA) and Genetic Algorithm (GA) in terms of solution quality and convergence properties. Obtained results demonstrate the validity of proposed method.