The interblade phase angle is one of key factors to act on the aeroelastic stability of steam turbine.A two dimensional numerical deforming actuator disk method on non constant interblade phase angle along circumferential direction has been developed to predict the stall flutter of the steam turbine.The effect of the interblade phase angler on the blade flutter of the steam turbine has been studied with the help of the developed method.The results indicate that when the interblade phase angle is between -45° and +90°

the stall flutter may occur at a certain condition.