A methodology of power system energy saving and economy operation evaluation for China Southern power grid is proposed，which takes into consideration the characteristics of the coordinated operation of multiple types of generators and massive electricity delivery from the west to the east.The methodology is based on the chronological operation simulation of power system.Several sub-modules for mid/long term operation simulation are proposed including operation simulation of renewable energy，generation maintenance simulation，and dispatch optimization of inter-basin cascade hydropower plants.A unit commitment model is also proposed by taking into consideration the operation constraints on the power system，practical scheduling rules，coordinate dispatching of multiple types of generations，and the modification of transmission losses.The proposed methodology facilitates a full view of the prospective operation for the power system on an hourly basis.The operating costs，fuel costs and carbon emissions of the power system over the whole planning year can be calculated based on the simulation results to achieve the energy saving and economy operation evaluation for the power system planning scheme.Finally，an IEEE-RTS 79 test system and one of the blueprint of Guangdong power grid for 2015 are used to validate the proposed methodology.