Abstract: In order to improve the mechanical performance of rectangular concrete-filled steel tubular (CFST) pier columns, double exocentric circular tubes are added inside to form a new composite CFST pier column. Seven specimens were tested under axial compression to analyze the new column’s failure mode, strain development, bearing capacity and ductility through comparisons with the hollow steel tubular column, rectangular CFST column and sandwich column. Then the axial bearing capacity improvement of the new composite CFST pier column was analyzed by investigating the confining effect between steel tubes and concrete. The results show that the new pier column under axial compression encounters the local bulging damage; its ultimate bearing capacity is 20% higher than that of the sandwich pier column, and 22% higher than that of the rectangular pier column; meanwhile the ductility increase is more obvious. The strain of inner and outer steel tubes was fully developed, which indicates that the steel tube realizes its vertical bearing capacity and transversely confines the concrete well in the composite CFST pier column. According to the normalized width-to-thickness ratio and post-buckling strength, the inner and outer tubes’ bearing capacity is increased by 15% with the concrete’s support, and concrete’s bearing capacity is increased by 49% due to the steel tubes’ confining, so the whole pier’s bearing capacity is increased by 31% owing to the confining effect. Compared with the test data, the absolute error of the bearing capacity calculated by the equivalent confinement coefficient is within 4%, indicating that the new composite CFST pier column also conforms to the unified theory of CFST. Therefore, the new composite CFST pier column has a significant improvement in confining concrete, bearing capacity and developing ductility, and thus has a strong engineering application prospect.