The invention belongs to the technical field of steel structure application, and particularly discloses a single-layer latticed shell steel structure roof system based on a concrete building and an assembling method of the single-layer latticed shell steel structure roof system based on the concrete building. The single-layer latticed shell steel structure roof system is formed by a cross-section-variable box type supporting assembly and a U-shaped top cover assembly. The single-layer latticed shell steel structure roof system based on the concrete building has the advantages that the structure is simple, and assembling is accurate, convenient and rapid; during installation, slant columns have the connecting effect and the supporting effect, and a rhombus structure composed of slant supports and intersected supports is stable and reliable in supporting; swing columns and circular supporting bases are connected with concrete for fixing supporting, and the bearing capacity of a supporting steel structure is improved; center-radiating type radial steel straining beams are adopted for a whole inwards-concave top cover steel structure, a tension-major single-layer latticed shell is formed, center rigid rings are arranged in the center of a top cover, convenience can be brought to connection of the radial steel straining beams and joint construction, and meanwhile trusses are adopted for arrangement so that the rigidity of the center rigid rings can be improved.