This paper proposed a beam-column composite connection configuration with a single axisymmetric steel beam section to reduce the brittle failure risk of the lower flange welds. The quasi-static tests of three 1∶2 composite connection specimens were conducted. The specimens with the standard steel beam section, narrower beam upper flange and wider beam lower flange with weakened the beam lower flanges only, and widened the beam lower flanges only were considered. The failure process, hysteretic behavior, strain development of key sections, energy dissipation and ductility of each specimen were analyzed in detail. Results showed that composite connection specimens with guaranteed weld quality had full load-displacement hysteresis curves at the loading point, and showed good energy dissipation performance. The plastic hinge of the specimen with widened beam lower flanges occurred in the steel beam section at the end of widened flange plates, and the beam lower flange gradually cracked and extended to the steel web in the process of repeated buckling. Under the positive bending moment, the neutral axis of the composite beam section was close to the beam upper flange, leading to a large strain level at the beam lower flange. The composite connection with a single axisymmetric steel beam section was conducive to moving the plastic hinge away from the column face and thus reducing the strain concentration at the beam’s lower flange. The quality of beam flange butt welds should be guaranteed strictly in practical engineering.