In the process of construction,after proper assembly,with the help of sliding rail,truss is transported to the site and then installed with the methods of hydraulic lifting and high-altitude installation.

In this article,authors introduce technical methods of high-level additional floors of high-rise buildings under complex conditions of downtown,and emphasize the roof grid structure high-level assembly technique,safety protection methods,and the central column connection technique and so on.

Through construction in Yulin airport,the paper compares merits and shortcomings of adopting high slip method and high bulk method for such kind of structure,it analyzes items needs attention for high slip method,so as to establish base for such kind of construction.