The　base　force　element　method　(BFEM)　is　a　new　finite　element　method.　In　this　paper,　a　degenerated　4-mid-node　plane　element　from　concave　polygonal　element　of　BFEM　was　proposed.　The　performance　of　this　quadrilateral　element　with　4　mid-edge　nodes　in　the　BFEM　on　complementary　energy　principle　is　studied.　Four　examples　of　linear　elastic　analysis　for　plane　frame　structure　are　presented.　The　influence　of　aspect　ratio　of　the　element　is　analyzed.　The　feasibility　of　the　4　mid-edge　node　element　model　of　BFEM　on　complementary　energy　principles　researched　for　plane　frame　problems.　The　results　using　the　BFEM　are　compared　with　corresponding　analytical　solutions　and　those　obtained　from　the　standard　displacement　finite　element　method.　It　is　revealed　that　the　BFEM　has　better　performance　compared　to　the　displacement　model　in　the　case　of　large　aspect　ratio.