The state before and after water entry of high-speed projectiles was analyzed based on water entry ballistics and hydrodynamics and the dynamics model of projectile longitudinal motion was built. The trajectory simulation during water entry process of high-speed projectile with various turbulent angular velocity was estimated. The change rules of trajectory and velocity of focus, pitch angle, pitch angular velocity were obtained, and the influence of turbulent angular velocity was analyzed. The results show that with increasing of tail slapping frequency, the immersion depth of the trajectory tail increases and the continuous time increases. Moreover with tail slapping frequency increasing, the pitch angular velocity after tail slapping increases, then the increasing extent decreases or the pitch angular velocity decreases slightly. The bigger the turbulent angular velocity is, the more times the tail slaps in the same time happen, the earlier the tail slapping happens, and the shorter the moving time of the projectile is in cavitation chamber.