Abstract: One of the practical method for predicting the stall flutter of the blade of a turbomachinery is a semi-empirical one（deformed actuator disk method）. The reliability and simplicity of this method have been verified by the authors. Because the unsteady flow in cascade passage is neglected in the actuator disk method, there are some errors in computation. To improve this method, the authors developed a semi-actuator disk method which can be used for stall flutter prediction. The simplified unsteady solution of cascade passage improves the actuator disk method. An example of computation has shown that the accuracy of semi-actuator disk method is better than that of the actuator disk method.