A horizontal projectile entering water device based on cannon is designed, and the influence of projectile head type on ballistic trajectory and cavitation characteristics under high-speed horizontal entering water condition is studied. The high-speed horizontal water entry tests of five different head types of projectiles are carried out. The whole process of projectiles entering the water is recorded with a high-speed camera, and the cavitation morphology, projectile trajectory and warhead deflection data are analyzed. The results show that for the five types of projectiles used in the experiment, the column section of the projectiles do not affect the formation of cavitations under the condition of entering water at a velocity of about 330m/s. In the process of entering the water, the warhead deflection of the 5 ° corner-cut nose projectile body is strong, and even a tail beat is produced. In the case of the same cone angle and water entry velocity, the diameter of the head end circle of the projectile body is proportional to the size of the cavitation profile. The research results have important reference significance for the head type optimization design of weapon equipment.