Abstract: Supercavitation can be viewed as a kind of technology that could boost the speed of underwater vehicles. The memory effect and its shape, planning force and other hydrodynamic forces of the cavity are investigated, based on the principle of cavity expansion independence. The cavitator orientation effect and cavity flotation are taken into account in computing the hydrodynamic forces of all parts of the supercavitating vehicle. The efficiency of the fin as the fin immersion depth changes is researched while the vehicle is traveling underwater. Then a more precise nonlinear dynamic model of a supercavitating vehicle is established. The stability of motions is analyzed by simulation. A nonlinear control strategy is designed to track a peculiar depth.