Abstract: The special Franics turbine for cooling tower is characterized as long and narrow flow passage and complex geometric surface of blades, inducing difficulties for 3D modeling. Aiming at a turbine of super-low specific speed for a cooling tower, we calculate the skeleton line of runner blades by MATLAB based on dual-element design theory, and the skeleton line of blades are unfold and thicken. Finally smooth blade model is generated by the 3D modeling function of UG. The results show that the proposed method can generate smooth blades, which reflects the geometric features of blades accurately and improves the efficiency and accuracy of blades design. The results could provide support for CFD analysis and performance optimization of turbines.