Abstract: Large water storages and diversion facilities can not be constructed at the ends of the two transportation lines of the Water Diversion Project from Tao River (WDP) in Gansu Province because of limit of engineering conditions. To solve this problem, water delivery time of the main channel has to be prolonged to winter. Based on the practical engineering condition and related heat and mass transfer theories, a three-dimensional numerical model for fluid-solid coupled convective heat transfer was established and validated by laboratory test result. The water temperature variation within the closed aqueduct under low-temperature condition in cold regions was predicted by solving the numerical model. The numerical results showed that the water temperature within the aqueduct was determined by the flow capacity, inlet water temperature, flow velocity, ambient temperature and et al. However, because of the effective design of the aqueduct, rational application of insulation and control of water flow time, the decrease of the water temperature was not obvious, and the water temperature in the aqueduct could be kept above 0℃, which ensured water supply in cold seasons. The study in this paper provides scientific reference for optimization design and safe operation of the other water diversion projects in cold regions.