Abstract: The linear Mohr-Coulomb failure criterion and the associated flow rules have been widely used in geotechnical engineering.However,the experimental results show that the strength envelopes of almost all geomaterials have the nature of nonlinearity and the associated flow rules are unsuitable to geomaterials too.Therefore,larger results would be yielded.Based on the upper bound limit analysis theorem,the nonlinear M-C failure criterion and non-associated flow rules,and the ultimate pull-out capacity(UPC) of horizontal rectangular anchors are studied by means of the kinematical approach of limit analysis theory.The non-associated flow rules are introduced by means of the modification shear strength parameters(φ and c) and the nonlinear shear strength parameters(internal friction angle φt and cohesive force ct) are treated as variable parameters too for the calculation schemes.From the numerical results,it can be seen that the shear dilatancy of geomaterials and the nonlinearity of failure criteria have significant effects on the pullout stability.Therefore,a proper assessment for mechanical characters of geomaterials benefits engineering practice.