The invention relates to an installation method for a large-span large-space steel structure roof truss. According to the method, large-span truss sectional hoisting and a truss accumulation sliding technology are adopted, and the installation precision is ensured by checking the concrete strength, sliding and unloading tool strength during truss assembly and the concrete strength during roof truss assembly through establishment of an FEM model before hoisting and sliding. The installation method for the large-span large-space steel structure roof truss has the advantages that not only the construction cost can be reduced, but also the installation period and precision can be better controlled through optimization construction of the existing sliding construction methods.