The system of long-span steel truss is widely used in steel structure applications,it is commonly used as a single-story long-span steel truss system, and its installation method is relatively mature. However, there are few installation projects of multi-layer long-span steel truss structure system, and its installation technology needs further study. The ground structure of the third-generation command center project in Shenzhen is a six-story continuous long-span steel truss system with a building height of 56 meters. Each floor is composed of six long-span steel trusses and steel beams, and the floor height is between 6. 5 meters and 12 meters. The project is located in a densely built urban area, and its storage yard and roads are very restricted. Through the comparison and selection of its installation methods, the construction methods of overall lifting and sliding installation were rejected, and the steel truss was installed at the corresponding position by a single-point support system with fast construction, safe and economical. By optimizing its structural form, the connection method and the top node, realizing the effect of quick installation and removal. The truss is arched during factory production, and the arching degree of the middle position is 60 mm during on-site installation. On the horizontal plane, the truss is installed in sections from south to north. On the elevation, a two-story steel truss is used as an installation unit. After the unit and the structure on both sides form a double-layer frame system, the lower truss support is unloaded and transported, and the floor is poured. After the floor is poured, the third floor of the truss structure is installed upwards, and the support system is turned up in this order for truss installation. Use MIDAS, which is a finite element analysis software, to simulate and check the force and structural deformation of the support system during the installation process in advance. Set deformation monitoring points at the middle and end of each truss, monitor and record it during the construction process. The results of data comparison show that the simulated value is basically the same as the measured value; The successful application of this support system in the third-generation command center project in Shenzhen fully proves that this support system is fast, safe and economical in construction. The installation of the truss adopts a two-story steel truss as an installation unit. After the unit and the two sides of the structure form a double-layer frame system, the lower truss support is unloaded and transported. This method can effectively control the deviation during the construction of the structure.