In this paper application of Particle Swarm Optimization (PSO) based algorithm for Optimal Power Flow (OPF) in Economic Dispatch (ED) was studied.Firstly, this method is dynamic in nature and it beats the arrears of other evolutionary computation techniques such as premature convergence and provides high quality solutions.Secondly, the aim objective is to minimize the gildan midnight fuel cost generation of Iraqi Super Grid (ISG400Kv, 24-bus) mizuno prospect gxc105 by using PSO.Third, the proposed algorithm had been tested based on two system; first tested theoretically (IEEE, 26-bus) and the second was tested practically the Iraqi Super Grid (ISG400Kv, 24-bus) with new data at October, 2010.Finally, the simulated results shows three major benefits of the proposed method on the systems studied as; Cost-minimization generation; Decreasing the energy loss and Enhancement of the voltage profile.