A research has been conducted on the defense system against dangerous rocks and rockfalls, with a particular focus on the prevention from falling rocks at the entrances and exits of railway tunnels. Firstlly, an analysis has been made of the hazards of the rockfall in Chengdu-Guiyang railway tunnel, thus identifying both internal and external factors affecting the formation of rocks and rockfall. Subsequently, a comprehensive defense system is proposed, incorporating such five layers of protective measures as active protection nets, stone barrier walls, passive flexible protection nets, rail barriers, and the extension of open tunnels. In addition, a novel design of steel tubular elements has been introduced, which utilizes its unique structural characteristics so as to achieve a compressive plastic deformation under axial load, thus enhancing the effectiveness of the rockfall protection system.