The surplus water head of the industrial cooling tower is generally 4 to 15 meters. Using the surplus water head, a Francis turbine with super-low specific speed is designed to replace the fan motor in the cooling tower, which may achieve the purpose of power saving. This turbine is different from the conventional turbine used in hydropower station. To drive the fan to a rated speed, the turbine is required to have high efficiency and small size to meet the installation requirements under a certain flow or water head. Little research work on this type of turbine has been done home and abroad. In this paper, the runner blade airfoil was chiefly designed by three-dimensional numerical simulation through the whole flow passage of the turbine. According to the features of the turbine’s work environment, metal elliptical volute and single row ring guide vanes were applied in the structural design. By comparison and analysis an optimal model of which the efficiency can reach 86% was selected to make the physical model. The model test shows that the designed super-low specific speed Francis turbine can meet the dimension requirement and has high efficiency of 85.3% and stable performance that can be popularized and applied in the capable local places. The new type Francis turbine with super-low specific speed studied and developed in this paper can achieve the goal of reducing the energy consumption of the cooling tower. It can provide reference of using the surplus energy to the other industry.

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