The shape of turbine blade has great impact on the performance of turbodrills. Take the example of turbodrill with diameter of 127 mm for geological drill; it is proposed to determine the configuration of the blade by quintic polynomial. Solidworks 3D modeling software was used in drawing three-dimensional model of the turbine blades. ANSYS FLOTRAN CFD was imported into the model, and hydraulic performances of the turbine blades under different viscosity were analyzed. From this simulation, abundant data of internal flow field have been obtained. Under CFD analysis, it confirms that the defects and hydraulic performance of turbodrill under different conditions are well demonstrated, which has guiding role for prediction of blade hydraulic performance.