Abstract: This paper, selecting a NWW Lianyungang-Yinchuan lithosphere crust-mantle composite struc tural profile, first tried to start from a simple mechanical model to use the two dimensional finite element meth0d to obtain the distribution characteristics of tectonic stress field in the lithosphere (crust and the top layer of upper mantle), thus interpreting the mechanical cause of the correlation of the imtroplate earthquake and lithosphere crust mantle strcture rate (R).