In the construction of large hydropower project, how to reduce supply risk and the integrated management cost of main materials supply is an important problem which the owner always faces with. Considering the supplier's supply capacity, supply risk and the management cost, an optimization mathematical model to minimize the sum of the risk loss of supply and management cost of the owner is established in this paper. Numerical example analysis shows that the model can determine the optimal number of suppliers according to the available data and achieves the integrated optimal of main materials management of the owner.