Abstract: Supercavitation technology is of great significance in reducing drag and enhancing the range of supercavitating vehicles. When a vehicle navigates in proximity to the underwater terrain, the rigid wall exerts a substantial influence on the cavitation enveloping the vehicle, thereby affecting its motion dynamics and stability. To elucidate the intricate interplay between the wall, shear layer, and the vehicle, this paper employs the VOF (volume of fluid) multiphase flow model, the Schnerr-Sauer cavitation model, and the realizable k-ε turbulence model to simulate the flow fields around a supercavitating vehicle in proximity to walls with and without the boundary layer. In the absence of a boundary layer on the rigid wall, the expansion of the cavities and the displacement of water are significantly hindered, yielding a much smaller cavities near the wall and a slightly larger cavities on the opposite side. Moreover, the supercavity exhibits a deflection towards the far side of the wall, which becomes more evident as the distance from the wall decreases, leading to a wetted lower surface of the vehicle. Conversely, in the presence of the wall boundary layer, the surrounding streamlines are deflected towards the low-speed, near-wall side since the upper side of the vehicle moves faster than the lower side. This results in a mitigation of the cavitatys asymmetry, with the upper side becoming convex and the lower side becoming flat. As the boundary layer thickens and the distance between the vehicle and the wall decreases, the shear effect around the vehicle intensifies. Consequently, the supercavity gradually deflects from the far side towards the near side of the wall, eventually evolving into an asymmetrical shape with a flat upper side and a convex lower side.