Existing studies have shown that the seismic performance of the mortise and grouting sleeve mixed connection assembled square pier (referred to as the mixed connection assembled pier) is close to that of the integral cast-in-place pier. In order to further explore the axial compression performance of the mixed-connected bridge piers, a series of axial compressive tests were conducted on one integral cast-in-place bridge pier (No. ZT) and four mixed connection and assembled bridge piers (No. GTA-0~GTD-0) with varying parameters such as the length, diameter and wall thickness of the steel pipes. The results show that the bearing capacity of GTA-0~GTD-0 specimens increased by 10.1% to 14.4% compared to the ZT specimens, and their ductility coefficients were all greater than that of ZT specimens. The axial compression bearing capacity of GTA-0~GTD-0 specimens increased with the diameter and length of the steel pipe, while the wall thickness of the steel pipe had a relatively minor impact on the bearing capacity. The damage position of the assembled bridge pier moves upward with the increase of the steel pipe length, gradually approaching the integral cast-in-place bridge pier, but the failure modes of the two are basically the same.