The axial performance degradation of 40 concrete-filled squared thin-walled steel tubular stub columns in severe cold and acid rain area were studied in this paper. The test parameters include freeze-thaw cycles (0, 80, 160 and 240), corrosion rate (0, 10%, 20% and 30%) and wall thickness (3.0 mm and 4.5 mm). The test process involves three parts: only acid rain corrosion test, only freeze-thaw cycle test and alternation test of acid rain corrosion and freeze-thaw cycle. The results reflect that the failure modes of the specimens were the local buckling of the steel tube and the transverse tensile fracture at the corner of steel tube. Derived from the test results, the development of the rigidity, ductility and strength reduction factor of concrete-filled squared thin-walled steel tube with the different parameters were discussed, as well as the lateral deformation coefficient of the steel tube and the confinement effect of the core concrete. After validating the design methods in different standards, the modified Chinese standard prediction formula was recommended to evaluate the ultimate strength of concrete-filled squared thin-walled steel tube stub columns under the alternating action of acid rain corrosion and freeze-thaw cycle.