Abstract: To investigate the axial strength of concrete-filled aluminum alloy circular tubular (CFACT) stub columns, six specimens with confinement coefficients of 0.57 to 1.26 were tested under concentric compression. The failure patterns, axial load versus axial strain curves, lateral deformation coefficient, peak load, and ductility were analyzed. The failure patterns included drum-shaped failure and oblique shear failure. The test results show that the columns exhibited a good composite effect between the aluminum tube and core concrete, and had high strength and ductility. An equivalent stress-strain relationship for the core concrete confined by the aluminum tube was proposed for the concrete plastic damage model, and a nonlinear finite element analysis (NFEA) model for CFACT columns was developed using the software ABAQUS. The NFEA model was verified by the test results. To reasonably design the CFACT columns, the axial strength of the CFACT stub columns was discussed and defined. Based on the NFEA model, the axial strengths of twenty-seven columns with different parameters including the confinement coefficient, diameter-thickness ratio, aluminum ratio, and material strength were obtained. Using the acquired axial strengths of thirty-three test and simulated columns, the cross-section composite strength was calculated. The ratio of composite strength to the concrete compressive strength was linearly related to the confinement coefficient. A formula for the composite strength was established by regression analysis.