Abstract: The National Stadium is one of the most importantstadiums for Olympics 2008. The stadium roof(114 m × 144.5 m) is two-way beam string structure (TBSS), a new andefficient spatial structure. To study the mechnical features of the structure, a 1:10 structure model of 11.4 m × 14.45 m is made. The following cases are includedin the experiment: different tension methods, different load casesand emergency load cases (such as when the cables are destroyed). Transverse cableforce, longitudinal cable force, stresses and deformation in thestructure are studied in detail.