Negative stiffness (NS) metamaterials have been widely studied in the fields of shock isolation and energy absorption due to their special properties. For various application scenarios, many types of NS metamaterials have been proposed, such as 2D honeycomb, 3D cube, hollow cylinder. However, when installation space is limited, the hollow cylindrical NS metamaterials may not achieve buffering effect due to its weak stiffness. In this paper, a cylindrical negative stiffness structure with inner hollow parts filled by inclined beam elements is proposed, which can obtain enhanced stiffness and energy absorption by improving space utilization. Theoretical analysis, numerical simulation and experimental validation were carried out to study the quasi-static and dynamic mechanical properties of the structure. Finally, the structure was applied as a cushion in a non-pyrotechnic separator, which could achieve good cushion performance. This work is expected to provide more potential for the applications of cylindrical negative stiffness structures.