Abstract: In the context of near-free surface supercavitating vehicle The method of combining theoretical analysis and numerical simulation was adopted to carry out the research on the dynamic mechanism of the near-free surface cavity evolution. A multiphase flow solver based on the OpenFOAM open source software platform was built to achieve two-phase numerical simulation of free-surface flow, ventilated cavitation and air entrainment. Simulation analysis of near-free surface cavitating flow for axisymmetric and projectile-wing combination configurations was carried out respectively. The effects of ventilation rate, projectile length-to-diameter ratio, sailing depth, sailing speed, etc, was further investigated and the mechanism of interaction between free surface and cavity was revealed. Furthermore analysis of the influence mechanism of the trans-media hydrofoil on the gas-liquid interface fluctuation and the pressure distribution of the projectile was obtained. It was found that the increase in the length-to-diameter ratio of the projectile will lead to an increase in the wavelength and a decrease in the amplitude of the cavity induced wave, which will help to improve the stability of the supercavity and enhance the drag reduction rate. When the Froude number is high, too large ventilation coefficient will lead to deflecting downward of the cavity central axis and the increase of the cavity flow area. The pressure drag will be increases significantly. For the projectile-wing combination configuration, the hydrofoil cuts the tail of the main cavity, which is easy to cause intermittent wetting of the tail section, and the amplitude of the wave above the main cavity is significantly reduced, indicating that the hydrofoil has a suppressing effect on the main wave.