The behavior of square-tubed reinforced concrete (STRC) short columns subjected to axial compression was studied in detail with an accurate nonlinear finite element model (FEM). Different width to thickness ratios (D/t =50-150) of the steel tube and the compressive strength of concrete (C80 and C50) were adopted in this research. The axial load strength, steel tube strain and load-shortening response were determined from FEM and the analysis results from FEM were compared with those from experiment. The analysis and test results indicate that the concrete strength little affectes the confinement of the steel tube on the concrete. The transverse stress of the tube at the axial load point increases with the increment in the width to thickness ratio. Based on the results from FEM and experiment, a formula for the prediction of the axial load strength was proposed in this paper.