In respect of the difference between domestic and foreign physical model tests in characteristic parameters of a mooring ship’s motion response periods, experiments are performed on a 266 000 m3 LNG ship under the function of transverse waves to study the characteristics of the ship’s motion response periods. The results show that a natural period to the ship’s surge motion is 32 s under the ballasted condition; the sway motion is a kind of intermittent periodic growth movement, the ratios of the periods of sway motion and the natural periods of the ship’s roll are between 1.11 and 1.23, which, in general, grow exponentially with the increase of wave periods. The peak values of rolling motion grow with the increase of wave periods. The ratios of rolling motion periods and the mooring ship’s natural rolling periods are between 1.23 and 1.48, which roughly grow exponentially with the increase of wave periods; the natural periods of yaw motions become longer under different loading conditions: 30 s for the ballasted condition, and 32 s for the laden condition.