Abstract: In order to reveal the size effect law of high strength concrete columns,axial compression experiments of high-strength concrete columns with different geometric dimensions and no stirrups were carried out.Based on the experiment results,failure characteristic,stress-strain curve,maximum carrying-load capacity,deformation capacity and stiffness of specimens with various dimensions were comparatively analyzed.The results show that as to high strength concrete columns without stirrups under axial loading,size effect exists in failure characteristic,maximum carrying-load capacity and deformation capacity,but not in stiffness degradation.