Abstract: In this research, the axial compressive experiments were conducted through 11 groups of prism specimens confined by square stirrups. The failure mode, stress-strain curve, peak strain and peak strength, and post-peak deformation capacity were evaluated; influences of the specimen size and the stirrups configuration on the mechanical properties of confined concrete were investigated. The change rule of the size effect along with the changes of the volumetric ratio of transverse reinforcement was discussed. Results show that for the specimens with the same volumetric ratio and the same configuration of stirrups, the peak strength, peak strain and post-peak deformation capacity decrease along with the specimen size increasing; for the specimens with the lower volumetric ratio of transverse reinforcement, the size effect on the peak strength is more obvious than that of the specimens mentioned above, while the peak strain and post-peak deformation capacity become comparatively weaker; for the specimens with the same volumetric ration of transverse reinforcement with various stirrups configuration, the increasing value of the peak strength for the larger size specimen become smaller, and it is smaller than that of the smaller specimen with the simplest stirrups configuration; while the peak strain and the post-peak deformation capacity increase greatly, which are larger than that of the smaller specimen with the simplestconfiguration. Comparing the peak strength for core concrete with the results calculated by using two typical models, it is showed that the results obtained from the typical models cannot predict the influence of the size on the peak strength perfectly.