Inorder to study the effect of cavitation grooves on the water-entry stability and drag reduction characteristics of projectiles under wave conditions, numerical simulations were carried out on the entry of three different shapes of projectiles with rectangular grooves, triangular grooves and no grooves on the projectile head. Study their ballistic stability, drag reduction characteristics and underwater cavitation shape and flow field distribution during their entry into water under wave conditions. The results show that the cavitation formed by the projectiles without cavitation grooves forms a closure relatively early, causing the projectiles to be unevenly disturbed, which has a certain impact on the ballistic stability and drag reduction characteristics. There is little difference in the ballistic stability and drag reduction characteristics from the other two types of projectiles with cavitation grooves,the rectangular cavitation groove has a better effect on the drag reduction characteristics of the projectile due to the eddy current formed at the groove than the triangular groove.