Abstract: The school library is a two-story above-ground building with a square plan， featuring a curved spatial steel structure. The main structure consists of 8 bidirectional orthogonal primary trusses， which span the full two-story height and are integrated with the architectural curvature. This paper introduced the arrangement scheme of the main steel structure， as well as its characteristics and design difficulties. Based on structural analysis， the dynamic characteristics and control conditions of the long-span steel structure were obtained， the horizontal displacement， vertical displacement， and component strength of the structure meet the requirements of the related codes. A buckling analysis of the main steel structure was carried out， and the load-displacement curves were obtained. The results showed that the main steel structure had a high stability safety factor and sufficient stability bearing capacity. Additionally， the steel structure demonstrated strong resistance to progressive collapse， ensuring that failure of local members would not trigger it. The the structure—featuring large cantilevers and spans—achieved a significant reduction in peak floor acceleration through the rational arrangement of tuned mass damper （TMD）， thereby meeting the comfort criteria. Finally， the typical steel structure joint design was introduced， and finite element analysis was conducted to verify its safety and reliability.