The deployment of projectiles in polar regions is significantly influenced by floating ice conditions during water entry. In this paper, based on the FSI method, the water entry process of the projectile is calculated for no ice and floating ice environments when the projectile enters the water at 100 m/s, and the difference between the cavity evolution and the impact load is compared. The computational method is validated through an experiment, and the calculation results are in good agreement with the experiment. Findings reveal that floating ice enhances cavity growth, prolongs closure duration, and elevates splash height near the free surface. Furthermore, projectile-ice collisions amplify impact forces, resulting in an 8.8% and 13.1% increase in peak acceleration and pressure, respectively, compared to the ice-free condition. These insights offer valuable guidance for the design of projectiles and vehicles in polar environments.