Abstract: A modification of mean-stream line method is presented. With this modifications an computation of two-dimensional cascade can be calculated analytically and the accuracy solution is higher than the original method as well as the time needed for one complete calculation is shorter. Some examples of solution are compared and discussed for finding the better form of the mean-stream line and the better variation of velocity alone the mean-stream line. With this discussion and the equations and tables presented in this paper; only about 8 hours are needed for projecting a good turbine, cascade circulated by compressible flows and the iteration in the direct problem to fit the given blade shape is more practical. The results of calculation of this method compared well with experimental. Data. Some probabilities of development of the mean-stream line method are discussed in tile end of this paper.