The main building of CCTV is a complex connection network with unique body shape, and it is difficult to process and fabricate components and install them on site. Especially, the cantilever part of the main building has the construction characteristics of large cantilever span, heavy weight, bidirectional inclined high-altitude folding butt joint, multi-joint special-shaped components, and high installation risk. This paper mainly introduces the detailed design of the net frame of the CCTV main building, the processing of the components, the installation of cantilever on site and the related net frame control technology. The main building of the new CCTV station has a total construction area of 470.300 million m-, which is a complex combination of the whole network. The total consumption of the network is about 140,000 t, including two Leaning Tower buildings, cantilever network connecting the two Leaning Tower buildings, as well as a 10-storey podium building and a 3-storey basement. Tower 1 has 52 floors, and the highest elevation of the roof is 237 m. The 44th floor of tower 2, the lowest elevation of the roof is 194 m; Podium building 10 floors, roof elevation 46.45 m. The network of the two towers is similar, consisting of core tube, internal network frame and outer frame tube. The inner core tube and inner column of the tower are vertical, and the outer frame tube of tower 1 and tower 2 are two-way 6. Tilt. Horizontal arrangement of column and foot. The cantilevered grid is the connecting part of the main building. It extends 67.165 m from the elevation of 162.2m (F37 floor) of the two towers respectively. The cantilever grid has 14 floors, with a width of 38.592 m and a height of 53.4 m at the farthest end. The total mass of the grid is 18,000t. With the addition of concrete floor, curtain design and decoration, the total mass of the cantilever grid is about 51,000t. The cantilever is composed of an outer frame cylinder, a bottom conversion layer and an internal frame grid. The bottom F37 and F39 floors adopt a combined floor with steel plates 6 ~ 20 mm thick. The construction of cantilever grid is complicated, and the cantilever closure is the key point of the construction. The cantilever closure in winter has a large cantilever span and is greatly affected by the temperature and other climatic conditions. The main components are: two-way tilt 6. ~ 8.45 "outer frame butterfly node steel column; On the bottom, 15 trusses of giant transfer trusses connected to the outer frame and the inverted l-shaped multi-joint heavy side beam; H - shaped steel column and steel beam of inner cylinder. The total number of cantilever steel members is more than 6000. The roof grid is 14. Inclined plane, the main form of components for box section. 2 construction detailed drawing design grid construction detailed drawing design using advanced XSTEEL and other detailed drawing design software and ANSYS, SAP 2000 and other analysis software, give full play to the advantages of the software, and through node secondary development and other means, so that the whole grid engineering deepening design progress and quality have been well guaranteed. The cross section of the outer frame column is complex and forms a butterfly joint with the outer frame steel beam and steel support. The XSTEEL deepening design model of part of the facade of the main building is shown in figure 2. Since most steel components are composed of various sections and different specifications of various materials, and the steel plate thickness is mainly 60, 80 and 100 mm, it is difficult to deepen the design of the components. Among them, the spot node design is the difficulty and key point of the deepening design. Affected by site construction environment factors and most of the site nodes of CCTV grid project are fully penetration welding nodes, the design of the nodes should meet the requirements of small welding deformation, small welding residual stress, feasible site operation and easy quality assurance. Component segmentation is a very important work in the deepening design of grid structure. According to the performance of the tower crane and the requirement of design, reasonable section and section are carried out in the deepening design. According to the actual layout of the deepening design, it is found that the overweight components are mainly concentrated in the outer frame cylinder column with butterfly joints. For this reason, the following treatment measures are adopted: firstly, the butterfly joints are separated, that is, the butterfly joints on one side or both sides are removed by on-site welding. If the method of separating butterfly node is still overweight, the method of separating column body is adopted. If overweight component column section of ontology for the stud (double box) cross section, are connected to the butterfly node plate of box column as a unit, the rest of the "Ⅱ" form separation unit as a unit, the unit using the welding way. If overweight column section of ontology to glyph components (3 cases) section, first of all, using that connected the butterfly node and box cylinder and middle box cylinder as a unit and the rest of the "Ⅱ" form for separation unit as a unit. Secondly, if the heavier element is still overweight after the separation with this scheme, a separate separation scheme is adopted to separate the butterfly node plate and the connecting box column as a unit from the rest of the column as a unit. It is indicated that the mass before separation is 98.3t, which cannot meet the requirements of the lifting capacity of the on-site tower crane. The column body is separated into two hoisting units of 65t and 33.3t in the deepening design. Due to the influence of tower tilting design and large cantilever truss, the main part of the grid will be deformed constantly during the construction process. The control goal of the grid configuration is to meet the requirements of the design drawing with the configuration and size of the grid after the constant load of the building is completed. Through the construction simulation analysis of the main building of CCTV, it is found that if the steel members are processed and manufactured in accordance with the layout diagram of the grid design, it will increase the difficulty of adjustment during installation, and there is a certain deviation from the proposed pre-adjustment range. In order to solve the deviation problem, it is necessary to take into account the pre-adjusted value of the deformation of the truss members in the design of the construction details and the manufacture of the components, and to take into account the actual deformation monitoring results in each construction stage, and to modify the pre-adjusted value. In addition to the ordinary h-shaped and box-shaped cross sections, many special cross sections have been added.