Abstract: The underwater vehicle will be subjected to strong impact load in the process of water entry，and the excessive impact load can easily cause structural damage and internal equipment failure. The technology of load reduction during high-speed water entry is studied. A cushion nose cap with prefabricated cracked carbon fiber material as outer cover and foamed aluminum as inner cushion material is designed.The numerical simulation is based on the finite element method，and the coupled Euler-Lagrange solver is used to study the load reduction effect of cushion nose cap.The effectiveness of the numerical method is verified by comparing the numerical results with the experimental images of a sphere entering into the water.The impact resistance，damage mode of cushion nose cap and the evolution process of cavitation bubble at different water entry speeds and angles are analyzed. The results show that the cushion nose cap shatters along the prefabricated cracks after hitting the water surface. The foamed aluminum is compressed and absorbs energy.As the cavitation bubble below the free surface expands outward，the broken nose cap spreads around the inner wall of cavitation bubble. The cushion nose cap has a good load-reduction effect on underwater vehicle at different water entry speeds，and water entry angles. Under the worst condition of vertical water entry，the load reduction rate is more than 75%.

Key words: underwatervehicle, waterentryimpact, loadreduction, coupledEulerian-Lagrangemethod, cushionnosecap, obliquewaterentry