Under the circumstances that the market mechanism of power is constantly changing, the transition period of the hydropower development tends to be more perfection. Considering the new connotation of the current environment of water power coordination, the core still lies on the profits of enterprises that manage the power grid. In this case, this paper proposes a united scheduling model in which the system of hydro-thermal hybrid power includes a stepped hydropower station. This model can suit the current generation, and the costs of short period power purchase are the lowest in the generation side. Differential evolution algorithm is introduced into the short-term optimal scheduling of the power system in China for the first time to make the energy production of hydropower and coal-fired power achieve the optimal allocation. Actual examples of calculated results show that the algorithm can achieve better economic dispatch under this model.