Abstract: This article deals With the initial research for three dimensional flow existed in conventional conical passage of turline. The first part investigates the influence of coningon the property of blading in large conic diffusing (or constricted) passage With turbine guide blade, on the condition that there is no movable blade at up and down-atream As a result' it is pointed that the change of the exhaust angle due to the deviation of actual stream surface from cylindrical surface must be considered in design for this,the author gives a approximate method for computing the variation of this exhaust angle, In the second part approximate design method for above-mentioned turbine: guide blade in consideration of three dimensional flow have been put forth.