In　order　to　improve　the　seismic　behavior　of　concrete　core　wall,　a　large　size　specimen　of　the　concrete　core　wall　with　aspect　ratio　of　3.14,　confined　with　reinforced　concrete　columns　outside　and　weak　steel　frame　inside,　was　tested　under　quasi-static　loading　to　investigate　its　seismic　behavior,　including　its　failure　pattern　and　mechanism,　hysteretic　behavior,　load-carrying　capacity,　elasto-plastic　deformation　ability,　and　stiffness　degradation　and　energy　dissipation　capacity,　etc.　The　test　results　show　that,　with　the　measures　of　the　external　reinforced　concrete　columns　and　the　internal　weak　steel　frame,　the　concrete　core　wall　is　confined　and　the　failure　of　the　concrete　is　postponed,　resulting　in　the　slowly　decreased　load-carrying　capacity　after　the　ultimate　load,　excellent　ductility　and　energy　dissipation　ability,　and　the　internal　weak　steel　frame　can　function　as　the　second　seismic　resistant　system　of　the　core　wall.　Therefore,　they　are　proved　to　be　the　effective　measures　for　improving　the　seismic　behavior　of　the　concrete　core　wall,　especially　in　its　post-yield　phase　of　loadings.