We designed an experimental underwater glider to survey the motion performance of the glider with passively rotatable wings. Table I shows major parameters of the experimental underwater glider. The glider is equipped with a pair of rotatable wings which can rotate about the wing axis(Fig. 2), and the angle of incidence can be altered from negative 30 to positive 30 degree. As is shown in Fig. 3(a), when the glider is ascending, wings rotate downward under the action of the hydrodynamic forces