Ultimate load capacity of slender concrete-filled steel composite columns is investigated in this paper. Nonlinear analyses are done by the use of finite element software, LUSAS, to study the ultimate axial load behaviour of the columns. Verification of the finite element modelling is done by comparing the result with the corresponding experimental result reported by other researchers. Analyses are carried out to assess different shapes and number of cold-formed steel sheeting stiffeners with various thicknesses of cold-formed steel sheets and their effects on the behaviour and ultimate axial load capacity of the columns. The results are presented in the form of axial load-normalized axial shortening plots. It is demonstrated that the ultimate axial load capacity of the slender concrete-filled steel composite columns can be accurately predicted by proposed finite element modelling. Obtained results from the study show that various thicknesses of cold-formed steel sheets, and different shapes and number of stiffeners influence the ultimate axial load capacity and behaviour of the columns. Also, the ultimate axial load capacity of the columns is improved by increase of number of stiffeners. Moreover, increase of thickness of cold-formed steel sheet enhances the ultimate axial load capacity.