Abstract: In order to compute the dynamic stiffness of low-pressure cylinder of the marine main steam turbine accurately, the center of the bottom of the cylinder was chosen as the loading point for a unit exciting force, as t his position could best represent the displacement of the whole cylinder model. The dynamic response under such load case was compared to that under another load case with the unit exciting force acting on bearing supp orts. The results show that the fist load case can be a better representative of the vibration of the whole cylinder and it is a practical and efficient loading way to obtain the dynamic stiffness more accurately.