Generally, the Load of upper structures is transferred to concrete foundations through columns supporting them. So, the anchor connection system is usually adopted in order to connect the columns and the concrete foundations. To apply this system, the column-foundation connections need to be designed with enough stiffness. This study was experimentally conducted to effectively improve the structural detail of circular CFT column-foundation connections, to which axial and lateral load simultaneously apply. For this study, the test specimen with a general anchor and an anchor frame, and the specimens with the high-tension bolt and inner reinforcement were fabricated. In addition, double base plates were adopted to have the enough stiffness of connections. The behavioral characteristics and the failure mode were investigated and compared, and the improvement of structural detail of circular CFT column-foundation connections was suggested.