Abstract: The determination of multi\|objective optimized scheduling of hydrothermal power system plays a very important role in operation of the entire electric network. Three forms of hydroenergy for large scale reservoir are analyzed firstly, and the power generation model of hydropower station is built, based on which the calculation model of unit electric energy output by water consumption volume is proposed. By considering power generation cost, novel cost function model for power generation is set up with introduciton of coal price. In the end, an optimal scheduling model that considers both objectives of least water consumption for whole power generation of hydropower station and least generation cost for thermal power station is built, and the optimized calculation is carried out. This model will be basis for optimal scheduling decision\|making for system dispatchers. And the calculation results of optimal simulation show that the scheduling criteria that are proposed in this paper are feasible and applicable.