Abstract: A simulation approach for loaded tooth contact analysis is presented.Deformation of the tooth,deflection of the supporting system,backlash between the teeth,gaps on points except temporary contact point,manufacturing and assembling errors are considered.In this procedure,the accurate geometry resulted from TCA is foundation of whole calculation,and the flexibility factor matrix by using finite element method is adopted.Besides,the non-linear contact analysis between multi-pairs of teeth can be done only through the mechanical and geometrical analyses of single-pair of teeth.