Abstract: In order to predict turbine rotation speed under the conditions of cavitation, obtain hydrodynamic performance data such as cavitation situation nearby turbine blades, pressure coefficient of turbine hub surface and drag coefficient of the projectile, the two-phase three dimensional flow field was investigated by numerical simulation method for underwater ammunition fuze turbine with high rotation speed. Schnerr and Sauer cavitation model was adopted, and the flow field data under different depths (10m, 30m and 50m) and projectile velocitiy (5~100m/s) conditions were obtained. The results showed that fuze turbine surface cavitation start to occur near the projectile velocity of 30m/s, and with the increment of velocity, cavitation scale increased. When the projectile velocity is 100m/s, the head viscous drag is about 18.7% of the total drag. The turbine rotation speed is related to the depth of water, static pressure and projectile velocity. The turbine rotation speed decreases significantly with depth of water at high projectile speed, and there has nearly a linear relationship between the turbine speed and projectile velocity, non-linearity of which is about 0.998.