Abstract: To solve the influences of constructions of bifurcated joint of mega concrete filled steel tubular columns(CFST), based on China Zun Tower, two specimens with different constructions under eccentric repeated load were conducted. The authors studied the failure modes, ultimate strength, flexural rigidity, deflection, and strain law. The results show that the bending damage is the main failure modes and is associated with the stiffness distribution and value of legs of bifurcated columns joint. Before the steel yield, the longitudinal strains of the leg perfectly accord with plane cross-section assumption, approximately according to it after the steel yield. Without considering the bearing capacity of diaphragms, it is non-ignorable for the difference of the tested value and calculated value coupling with confined effect of steel, which states the stronger composite confined effect between multi-cell steel tube and diaphragms at compressive zone.