A slender steel frame system composed of steel members with a high width-to-thickness ratio was adopted to achieve lightweight steel residential structures. By carefully selecting the section configuration the system achieves a balance between load-carrying capacity and ductility. To study the seismic performance of the slender steel frame system, two full-scale frames are constructed. These frames include members with S1, S3 and S4 configurations, varying in their cross-section width-to-thickness ratios. The frames are subjected to cyclic tests to analyze their failure mechanisms, hysteresis curves, load-carrying capacity, ductility, and energy dissipation capacity. The test results indicate that both specimens were mainly damaged by local buckling deformation at the beam end and column bottom region, with the initial concentrated damage occurring at the beam ends, leading to the specimens reaching their ultimate bearing capacity state. In addition, the sequence and degree of buckling deformation significantly influence the seismic performance of the frames. The slender steel frame structure, when combined with components of different width-to-thickness ratios, can achieve lightweight design while maintaining satisfactory ductility and plastic energy dissipation capacity. Finally, based on the experimental results, finite element models of the specimens were established using ABAQUS. Parametric analysis was conducted to determine the failure mechanisms and corresponding internal force variations of the buckling sections under different section configurations.