Abstract: With the development of urban rail transit and the deepening of integration of under-and above-ground urban space, the rail transit co-construction project has become a new direction of the public transportation-oriented development mode. Relying on the Dongguan Xiping Station project, a combined structural scheme was designed for the long-span building cover and conversion beam area, which could reduce the height of beams by 28%-33%, the dead weight by 49%-66%, and the cost by 7%-36%. The overall model of the steel reinforced concrete structure and the steel-concrete composite structure were established and the seismic performance analysis of the two structures under different earthquake was carried out by YJK and MIDAS Gen. The composite structure decreased the interlayer displacement angle under rarely occurred earthquake, which suggested that it showed a better seismic resistance while maintaining natural vibration characteristics similar to the steel reinforced concrete structure. It was notable that the bending-torsional coupling effect in the transformation beam area is significant, resulting in the torque reached up to 2 719.4 kN·m; and the stress of the long-span steel structure reached up to 207 MPa.