For self-anchored suspension bridges, reasonable auxiliary span setting, cable force optimization, and structural system selection can not only effectively eliminate the negative reaction effect at the anchorage end, but also improve and optimize the mechanical performance of the stiffened girder. However, current theoretical research is mostly focused on large-span bridges crossing rivers, lakes, and seas, with fewer applications and a lack of corresponding attention in the field of small- and medium-span bridges. In particular, theoretical research on single-tower structures is relatively scarce. In this paper, combined with a practical engineering project, the bridge was studied using a simulation analysis method based on the mechanical performance of the main bridge. Recommended values for the setting length of the auxiliary span, the bearing proportion of cable force, and the selection of the structural system were provided, which can serve as a reference for the design of other similar projects.