Increasingly large and complex structures make it more complicated in analysis, designing and construction, and through the amplification effect caused by the interaction of various parts of the structure, any tiny error in any link could cause huge damage to the building. However, the relative analysis theory and design method are not consummate enough to assess the influence of all kinds of errors. Under this circumstance, structural health monitoring system is an important guarantee to ensure the safety of the structures in both construction and operation stage, and at the same time contributes to make up for the deficiency of theory [1-2]. The Expo Axis project is the largest single project in Expo Site 2010 Shanghai. The Expo Axis project has adopted a whole new architecture form. The roof design as giant light cable-membrane structure about 1000 meter long and about 80 meter width. The computing displacement of the membrane roof is close to 4m. In order to ensure the safety of this structure, a real-time and long-term computer based health monitoring system is applied in the Axis structures.