Singapore Cool Dry conservatory is a huge space steel structure which is for exhibiting plants suited for living in cool and dry conditions. Due to its seashell shape, it adopts arch-shell hybrid structural system. Double-layer glass curtain walls are suspended to the shell, while cables are tensioned between large arches to increase lateral stability capacity. Because of this structure’s specialty, traditional structural design software in China can not meet the need. FEA software ANSYS was employed to make design optimization, and make further verification. The global stability bearing capacities considering geometry non-linear elasticity and elasto-plasticity conditions were evacuated and analyzed.