The steel tubular column filled with steel reinforced concrete (SRCFT), is formed by inserting a steel section into a concrete filled steel tube. In the current paper, a new shape, namely Castellated Cruciform Steel Section (CCSS), for reinforcing of CFT columns has been proposed to improve the compressive strength and hysteresis behavior of these columns under moderate and severe earthquake excitations. A comprehensive study has been conducted to investigate the strength of SRCFT columns reinforced with castellated and traditional cruciform steel sections, made with thin-walled, welded I-section. The paper describes and presents the results of the testing of four small size (155 mm*155 mm) and short column specimens. The experimental results indicate that the new steel section causes high strength and better post yield behavior of SRCFT columns, because of the increase of shear and bending strength, torsion resistance and interaction between the hollow steel section and concrete. In addition, the axial compressive capacities of those steel sections are investigated in a numerical way in the current study. The obtained results of nonlinear analyses of these columns revealed that strength and buckling behavior of castellated cruciform steel columns far outweighs and is more appropriate than that of the traditional cruciform steel columns.