The utility model discloses a roof framework building structure system of transformer substation that lattice formula crossbeam is connected, including GIS room roof framework and the transformation frame of connection on this GIS room roof framework, transformation frame includes the first framework unit of a plurality of interval arrangements, second framework unit and connecting in first, lattice formula crossbeam between the second framework unit, it is first, second framework unit forms by back allotment dagger and preceding bearing diagonal support connnection, the vertical connection ofback allotment dagger is on GIS room roof framework, preceding bearing diagonal post slope is connected on GIS room roof framework, be connected through the web member between back allotment dagger and the preceding bearing diagonal post, the back allotment of first framework unit props the back allotment dagger of column height in second framework unit, lattice formula crossbeam is connected bysteel pipe chord member and angle steel web member, establish a plurality of wires on the back allotment dagger of first, second framework unit and hang the point, and the raised area of allotment dagger still establishes the ground wire and hangs the point behind the first framework unit, establishes a plurality of wire jumpers on the lattice formula crossbeam and hangs the point.