In face of the peak load regulation problems of the power system with complex generation structure in an energy-saving generation dispatching environment，an optimization model for daily peak-load regulation is developed with minimum coal consumption，power purchase cost and SO2 emission as the objective，and an overall consideration given to various practical engineering constraints，such as the output power limits，regulation speed，and maintenance scheduling of generation units，etc.By means of units sorting，the start-up of those with better energy-saving effect must be given the highest priority.Through the determination of the unit commitment and the generation curves' calculation of pumped-storage units，the minimum start-stop times of units is realized.By optimizing the reserve capacity and modifying the unit output limits，the requirements for quickly treating load changes are met.The optimal scheduling of unit power output has brought about increased economic benefit and energy-saving benefit.The data from Guangdong power grid in 2010 show the feasibility of the model developed.