Abstract: Based on the VOF multiphase flow method, IDDES turbulence model and Schnerr-Sauer cavitation model, a numerical simulation model of a projectile with tail fins inclined into the water is established to reveal the influence of water entry angle and tail fins on the transverse impact load and ballistic characteristics of high-speed projectiles. Horizontal water entry tests were conducted using a 120-mm balanced gun launcher, an assembled water tank, a high-speed camera system, and acceleration recorders. The test projectile consisted of a nose cavitator, a middle conical section, an aft cylindrical section, and tail fins. The underwater motion attitude and cavity evolution of the projectile were captured, and the triaxial impact load histories were recorded. By comparing the cavity evolution and transverse impact load time histories between the experiment and simulation, the computational accuracy of the simulation model was validated. And the mesh independence of the simulation model was verified. The validated model was then used to investigate the effects of different water entry angles, projectile densities, and the presence or absence of tail fins on the transverse impact loads and ballistic characteristics during high-speed oblique water entry of a cylinder-cone projectile with an angle of attack. The results show that the projectiles with different entry angles underwater all undergo several tail-slapping motions, with the low-angle entry has lower underwater environmental pressure, thus increasing the underwater penetration distance. Increasing the projectile density increases the number of tail slaps and prolongs the tail-slap period, thereby increasing the penetration distance. Increasing the projectile density also reduces the transverse overload and leads to slower velocity attenuation, substantially increasing the penetration distance during the tail-slap stage.