Most researches have been done in gas turbine system(Buker, R. S. 1992, Staub, F. W. 1992, Green, T. 1992, Gamabe, K. 1992). However the phenomena for slots on discs in rotating system has not been discussed. In this paper, a 3D incompressible laminar code in cylindrical polar coordinates, based on both a stationary frame and a rotating frame is implemented. Two cases are studied: One is the sealed-rotor stator, and the other is rotor-stator with pre-swirl flow. The computed moment coefficients based on the two frames are within 4.5% of the empirical correlation.