Abstract: This paper presents a description of tests and finite element analyses for the aseismic behavior of 15 oblique joint specimens in which cold-formed back-to-back double C steel sections with gusset plates were used. The effect of a gusset plate thickness, bolt spacing, C steel thickness and web height is discussed. This joint showed a good aseismic behavior and high ultimate resistance. There are two failure modes: beam flexural buckling and gusset plate flexural-torsional buckling. The gusset plate thickness is the main factor for the joint failure mode. As the increase of the C steel thickness, web height and bolt spacing, the oblique-joint-ultimate bending capacity and initial stiffness increase too. Among these factors, the web height affects the most. The bolt spacing ranging from 11d₀ to 13d₀ is proposed and the thickness of the gusset plate is not less than 6mm. A total of 16 orthogonal specimens were analyzed. The relationship between semi-rigid characteristic values and parameters are discussed by numerical analysis. The conclusion would be a reference for design.