Using　the　concept　of　the　base　forces,　a　new　finite　element　method　(base　force　element　method,　BFEM)　based　on　the　complementary　energy　principle　is　presented　for　accurate　modeling　of　structures　with　large　displacements　and　large　rotations.　First,　the　complementary　energy　of　an　element　is　described　by　taking　the　base　forces　as　state　variables,　and　is　then　separated　into　deformation　and　rotation　parts　for　the　case　of　large　deformation.　Second,　the　control　equations　of　the　BFEM　based　on　the　complementary　energy　principle　are　derived　using　the　Lagrange　multiplier　method.　Nonlinear　procedure　of　the　BFEM　is　then　developed.　Finally,　several　examples　are　analyzed　to　illustrate　the　reliability　and　accuracy　of　the　BFEM.