The efficient population utilization strategy for particle swarm optimization (EPUSPSO) is proposed to solve the economic load dispatch (ELD) problem of power system with different units. This algorithm improves the accuracy and the speed of its convergence by changing the number of particles effectively and improving the velocity and position equation. To verify the effectiveness of the algorithm, this algorithm is tested in the ELD case of power system with different units, and the obtained results are compared with those obtained from other algorithms. The compared results show that the algorithm can find the optimal solution effectively and accurately, avoid falling into the local optimal problem; meanwhile, faster speed can be ensured in the case.