A　cantilever　holder-girth　(CHG)　flexible　connector　was　proposed　for　improving　the　adaptability　of　precast　concrete　(PC)　external　wall　panels　to　the　deformation　of　the　steel　frame　under　severe　seismic　loads.　Three　specimens　of　full-size　single-span　two-story　steel　frames　with　PC　external　wall　panels　(composite,　open-window,　and　integral)　were　designed　and　tested.　Low　cyclic　loading　was　applied　to　the　steel　frame,　and　a　horizontal　force　was　applied　to　the　external　wall　panels　as　inertial　force.　The　results　showed　that　the　external　wall　panels　with　flexible　connectors　had　good　adaptability　to　the　deformation　of　the　steel　frame.　The　maximum　deformation　of　the　CHG　flexible　connector　reached　27.16　mm　even　when　the　external　wall　panels　were　subjected　to　rare　earthquakes　such　as　a　magnitude　9　earthquake.　The　displacement　angle　of　the　external　wall　panels　was　only　0.0026　rad　when　the　steel　frame　reached　a　2.4　%　story　drift　angle.