Based on systemic study on the geometrical nonlinear finite element theory (C.Oran beam-column theory and T.L. method/U.L. method) of spatial structures, A geometrical nonlinear finite element method and some discussion is presented in this paper, a new phenomnon that C.Oran beam-column element can not solve cantiliever only bearing monment is firstly put forward and discussed. A nonlinear finite element program has also been developed by adopting VC 6.0 language.