How do calculation stability problems problems for large conical stiffened with longitudialribs,cannot yet issue in repord. In this paper,by applying the Hermite and trigonometricseries interpolation along the longitudinal and circumferential direction respectively,a newkind of geometrically nonlinear ring elements stiffened with ribs has been developed.The se-mi-discrete analysis method for the stability of large conical shell stiffenet with longitudinalribs is propose. The correctness and effectiveness of the analgsis is verified by examples.Thus,a kind new theory and method for establishment variaus kind semi-analytical elementsof engineering structure is proposed.