Abstract: According to the experimental investigation on three specimens of abnormal interior joints under low cyclic reversed loading,the failure process and patterns were obtained.The failure characteristics,mechanical behaviors of abnormal joints such as the load displacement hysteretic loops,rigidity deterioration and energy dissipation were analyzed.The experimental study was conducted that focused on the effect of joint hoop percentage and vertical haunched beam on seismic behaviour of abnormal joints.Test results indicated that joint shear failure process of the specimen was delayed by the application of vertical haunched beam,and the behavior of this new type joint was improved greatly due to the flexural failure formed in the connection between the low beam and the expanded joint core.