Abstract: To investigate the influence of the density of crushed ice region on the cavity evolution of the structure, the oblique water-entry experiment of the structure was conducted by high-speed photography technology under different crushed ice cover densities. Moreover, by compared the water-entry process of oblique structures in varying densities of crushed ice cover, the influence of crushed ice cover densities on the cavity evolution for the oblique water-entry process of the structure was obtained. Results indicate that during the cavity expansion, the presence of crushed ice reduces the cavity diameter by impeding the outward expansion of the fluid near the free surface, compare with the ice-free environment. When the cavity closes, crushed ice also impede the inward contraction of the free surface fluid, and prolong the time of the expansion of the cavity. The augmentation in the total volume of air within the cavity results in a decrement of the pressure differential between the inside and outside of the cavity, ultimately leads to a retardation in the closure time of the cavity. As the coverage density of crushed ice gradually increases, the impedance exerted by the crushed ice on the inward contraction of fluid at the free surface progressively intensifies. This enhanced obstruction from the crushed ice further prolongs the closure time of the cavity, concurrently augments its length and maximum diameter. In conditions of lower crushed ice densities, jets point to the interior of the cavity when the cavity collapses. Besides, under conditions of higher crushed ice cover densities, the cavity wall is wrinkled by the irregular impact of the fluid. As the submerged depth of the structure increases, the cavity undergoes a deep necking phenomenon under the influence of ambient pressure. As the coverage density of crushed ice gradually increases, The velocity of the underwater motion of structures shows a trend of faster decay compared to ice-free environments.