Steel structure sliding and column replacing construction method of large building roof lighting atrium

The invention provides a steel structure sliding and column replacing construction method of a large building roof lighting atrium. A steel structure is hoisted from a hoisting place to a roof surface, and sliding rails are laid and fixed; a work platform at one end of the roof surface is segmented, and two roof truss strip steel columns are combined to form a unit to be spliced, lifted and hoisted to the sliding rails; the sliding rails serve as guide rails so that a whole roof truss can sequentially move forward and slide by a distance of one truss through fixing points; then the whole roof truss is connected with a third roof truss and then slides forward, the roof trusses move from far to near repeatedly till all the roof trusses move to the specific positions; temporary switching steel columns are added again to the positions with unequal elevations locally, then the roof trusses continue to slide to target positions, and the whole roof truss continues to slide to a final position; finally, the whole roo