Abstract: For calculating stress of bns body structure, a thin-walled eccentric beam element witch accords with demands is introduced in this paper.The eccentricity existing in truthful structure. is directly calculated in finife element stiffness matrix, so the analysis of bus body structure is more effective, which offer a truthful data for design of bus, The well performance of the thin-walled eccentric element has been proved from a example of a real bus body analysis.