Abstract: Axial compression tests were conducted on seven specimens, comprising six cross-shaped multi-cavity composite concrete-filled steel tubular (CFST) stub columns and one conventional cross-shaped CFST stub column. The investigation focused on examining the influence of section form, width-to-thickness ratio, and flange height-to-thickness ratio on the compressive performance of the specimens. The test results showed that the columns presented local buckling damage at their middle and lower parts. The rigidity, ultimate bearing capacity and restraint effects on core concrete of cross-shaped multi-cavity composite concrete-filled steel tubular columns were better than those of ordinary cross-shaped concrete-filled steel tubular columns with the same steel ratio. The compressive stiffness of the specimen decreased with the increase of section width-thickness ratio. The ultimate bearing capacity of specimens increased with the decrease of sectional width-thickness ratios, and with the increase of height-thickness ratio of flange, but the increase amplitude was gradually reduced. Studies have shown that current domestic and international codes generally yield conservative calculations for the axial compressive capacity of cross-shaped multi-cavity composite lightweight CFST stub columns. Based on the Unified Theory, this paper proposes two simplified formulas for calculating the axial compressive capacity of such columns. Experimental verification demonstrates that the calculated results agree well with experimental values, with an average relative error within 2%.