Frame structures with exterior verandahs, which are mostly built in densely populated areas such as teaching buildings and dormitories in southern China, are a special form of frame structure that must continue to be developed. However, compared with other frame structures in many post-earthquake fields, this type of building designed following the Chinese code has demonstrated poor seismic performance, leading to a significant number of casualties and property losses. Therefore, to complement the design requirements of this structural type in the present Chinese code, the seismic performance of this structural type needs to be improved and optimized. A typical double-span RC frame structure with an exterior verandah in the Lushan Earthquake as the structure prototype was selected in this paper. PKPM software is used to obtain design information for the structure prototype, and the finite element model is established by utilizing ABAQUS software for simulation and analysis. A series of various optimal conditions are created at the base of the structure prototype’s simulation results, and a thorough investigation of the structural seismic performance under each condition is performed. Eventually, suggestions and proposals for future Chinese codes concerning the structurally optimum design of this structural type are provided.