Abstract: The cold-formed steel is widely used in low story residential structures, and corresponding specifications had been published; however, the codes for the design of compound sections are lacking currently. This paper presents the testing of bending joints whose sections are composed of cold-formed back-to-back double C steel with gusset plates, and finite element analysis are performed to investigate the seismic behavior of bending joints. The influences of gusset plate thickness, bolt pitch, C steel thickness and web height are considered. The failure patterns of these joints conform to anti-seismic design requirements. The hysteretic curves demonstrate high initial stiffness, significant stiffness degradation, good energy dissipation capability and good ductility. Gusset plate thickness and bolt spacing have great impact on seismic behavior. Increasing C steel thickness and web height can significantly improve the ultimate bearing capacity. Increasing bolt spacing can slightly improve the bearing capacity while the energy dissipation capacity is weakened.