Abstract: This paper is the continuation of the work done by Pan Liang-ju and his colleagues[2].Although they have improved and simplified the calculation method based on three-diman-sional theory in designing the rotary vanes of a Francis water turbine, yet computn- tions are too troublesome to be carried out by the common computer. The author of this paper continues the stuby further by malting use of the high speed electronic digital computer. In the course of calculation,. Their method have been complemented anti improved in some respects. All the sections of the rotary vanes have been calculated; the coefficient of cavitation of turbine have also been estimated. With given hydraulic and geometric parameters, the calculation results show the vane with smooth shape and the ranuor with lower coefficient of cavitation. By the help of the clectronic computer, the tendency of variation of coefficient of cavitation with respect to the hydraulic and geometric parameters have also been obtained and given in the paper. At the end, the results and method of calculation are discussed.