Ventilated supercavity technology is an emerging technology that can improve the velocity of underwater vehicle. In order to study the maneuverability of ventilated supercavity in longitudinal plane rotation motion of the vehicle, based on the finite volume method, a three-dimensional computational model of unsteady ventilated supercavity flow was established by using VOF multiphase flow model and RNG k-e turbulence model and utilizing the numerical simulation software Fluent. By solving the Reynolds averaged Navier-Stokes equation of multiphase mixtures, the unsteady multiphase flow characteristics of the cavitator model in longitudinal plane rotation motion were analyzed. The morphological changes of the ventilated supercavity and the relationship with the pressure distribution around the supercavity were obtained under the rotating motion of the longitudinal plane. The calculation results show that the ventilated supercavity was flexed by centrifugal force during the rotary motion, and the axis of the supercavity was gradually coincident with the motion track of the vehicle. The maximum radius of the supercavity gradually decreased when it rotated downward and gradually increased when it rotated upward, and the radius of rotation had a great influence on the shape of the supercavity in the downward rotating motion. In addition, the deflection direction of the closed position of the cavity tail was different. When the bubble tail rotated downward, it drifted outward, and when the bubble tail rotated upward at a small angle, it drifted inward. Due to the centrifugal force and the reverse pressure gradient in the axial direction of the supercavity, the slenderness ratio increased significantly during the upward rotation and decreased slowly in the downward rotation process.