Abstract: To study the seismic behavior of concrete core walls, two large size specimens of concrete core wall with aspect ratio of 3. 14 and axial load ratio of 0. 4 were tested, horizontally applied to uniaxial and biaxial pseudo-static loadings, respectively, to investigate the effects of biaxial cyclic loadings on their failure pattern, load-carrying capacity, deformation ability, stiffness degradation, energy dissipation, etc.It shows that both specimens fail in flexure at the bottom of the wall; compared to the case of uniaxial cyclic loadings, the effects of biaxial loadings result in significant decrease of load-carrying capacity and deformation ability, and faster stiffness degradation. The increase of energy dissipation with biaxial loadings as compared to that with uniaxial loadings is mainly due to the early damage and failure of the bottem of the wall, and the energy dissipated from plastic hinges of coupling beams in the case of biaxial loadings is less than the latter.