: In order to study the axial compression performance of the composite wall formed by self-tapping screw connection between the cold-formed square steel tube and the paper straw boards (straw board), the axial compression test of the three-sided composite wall was carried out, and the axial compression bearing capacity and failure mode of the composite wall were obtained. The experimental results show that the failure mode of the composite wall is the local buckling failure of steel tube and the local folding and bending of straw broad. The cooperative performance of square steel tube and straw boards is good. The straw board plays a good restraint role in the steel tube, and the bearing capacity of the composite wall is high. The nonlinear finite element analysis of steel-straw board composite wall was carried out by using finite element software ANSYS, and the numerical analysis results were in good agreement with the experimental results. On this basis, the effects of steel tube wall thickness, wall height to thickness ratio and tapping screw spacing on the bearing capacity of the composite wall were analyzed by using the finite element model, and the calculation formula of axial compression bearing capacity of the composite wall was put forward. The calculation results showed that the formula could well calculate the bearing capacity of cold-formed steel tube-straw board composite wall.