Abstract: A new type of composite strengthened method is developed by using a self-compacting concrete filled circular steel jacket to strengthen a RC column. A total of nine RC columns strengthened with self-compacting concrete filled circular steel jackets were tested under axial compression loads. Based on the measured strain of a steel tube and a steel bar,the stress of the steel tube,the concrete and steel bar are analyzed. The results show that the loading mode has a significant influence on the transverse deformation of a steel tube,and that the transverse stress of a steel tube loaded only on core concrete is better than that on the full section. The raising coefficient of core concrete strength and the distribution relationship of axial forces between the core concrete,steel tube and steel bar are affected by the loading mode,the steel ratio,the compressive strength of strengthening self-compacting concrete and interface bond.