Abstract: A series of high-speed projectile experiments were conducted to investigate the characteristics of natural supercavitation. Different models were designed for the experiments, the velocities of which range from 0 to 70 m/s. According to the velocities of models, a minimum cavity number of 0.04 could be achieved. The dependence of the characteristic parameters of natural supercavitation on the cavity number was obtained by analyzing the experimental data. It is shown that the diameter and length of natural supercavitation decreased with cavity number by exponential law. At the conditions of small cavity number, the dependence is consistent with the reported empirical formulas. The results show that high-speed projectile experiment is one of the most effective methods for investigating the characteristics of natural supercavitation, which may be used to capture many hydrodynamic phenomena.