Abstract: Mohr-Coulomb yield criterion, which does not consider the contribution of intermediate principal stress to soil strength,is a conservative yield criterion, thus Drucker-Prager yield criteria transformed from the Mohr-Coulomb yield criterion under approximate plane strain condition, will give conservative estimation of safety factor for plane strain slope stability analyses. Relatively, Matsuoka-Nakai and Lade-Duncan yield criteria both consider the influence of the intermediate principal stress on soil strength effectively, thus Drucker-Prager yield criteria transformde from the Matsuoka-Nakai and Lade-Duncan yield criteria under approximate plane strain conditions, could give a reasonable failure strength predictions for geo-materials, soil shear strength could be exerted more sufficiently under plane strain status, and therefore more reasonable and real safety factors could be exerted more sufficiently under plane strain status, and therefore more reasonable and real safety factors could be obtained by using the transformed Drucker-Prager yield criteria for slope stability analyses. Calculation results of planme strain slope stability given by using ANSYS prove above views.