Abstract: It is proved to be an efficient way to improve energy supply in rural area by developing wind, hydro and solar energy. But how to optimize configuration properly is still an immediate problem to be solved. The generating unit models for wind and water power are statistic random models based on inverse transformation from random sampling of wind speed and water flow, and what’s more, the optimum disposition model of rural hybrid generating system based on random chance constrained programming is proposed. The disposition model are to minimize investment capital and operational costs per year, and to maximize the utilization of resources and the reliability of power supply, which is also subjected to power balance and constraints of local resources. A Monte Carto-GA approach for solving the generation disposition problem is given, and the solution is a set of optimum plans listed by an annual rate of resource utilization, the loss of load probability and the loss of power supply probability. An application case study is given to prove the feasibility of the model.