Earthquake　action　is　multi-dimensional　and　random.　Under　bidirectional　horizontal　direction　loading,　the　seismic　capability　of　beam-column　joints　in　reinforced　concrete　(RC)　frame　may　be　lower　than　the　design　capability　under　unidirectional　main　direction　loading.　Detailed　calculation　methods　for　the　shear　bearing　capability　and　shearing　performance　of　RC　space　joints　in　frames　under　bidirectional　horizontal　direction　loading　have　not　been　reported.　In　this　work,　the　shear　mechanism　and　internal　force　calculation　method　of　an　RC　space　joint　under　bidirectional　horizontal　direction　loading　are　analyzed.　Furthermore,　a　shear　capacity　calculation　model　is　established　based　on　the　strut-and-tie　model.　The　prediction　of　the　shear　capability　in　this　work　are　in　good　agreement　with　the　reported　experimental　results.　This　study　provides　a　design　method　for　the　seismic　design　of　RC　space　frame　joints,　and　provides　a　supplement　for　the　seismic　design　method　of　RC　space　frame　with　＂strong　joints　and　weak　members＂,　when　they　are　subjected　to　bidirectional　horizontal　direction　loading　at　the　same　time.