Under the action of shock wave due to non-contact underwater explosion, ships with small size or large stiffness will have the response of large rigid-body motion. Based on Taylor plate equation, and taking the additional mass of transverse motion into account, the kinematic equations of 2D cross-section under the shock wave action due to the non-contact underwater explosion were established. And the response of the rigid body motion of a ship to the explosion was calculated. The results are in good agreement with the experimental data, which shows that the present method can be applied in prediction of motion response of ships under shock wave action.