As far as the issue of vibration isolating of ship, this paper studies the feedback control theory of hydraulic servo isolation mounting and sets up the theory model of two_stage isolation mounting.

The paper predicts dynamic response of the aft-part vibration of an "A type ship", using the hydroelastic theory, by the means of the set of computational programs designed by the authors.

The free vibration character of a shallow draft ship is successfully calculated. The results show that the theory and method described in this paper are of important practical value.