When the finite element strength reduction method is applied for analysis of slope stability, the resultant safety factors of slope rely on the criteria of instability. Usually the abruptness of displacement of feature parts, connectivity of plastic zone and convergence of numerical calculation are taken as the judging criteria of slope instability. However, there were different views for applications of these three criteria. This paper compares and analyzes the magnitudes of safety factors of three common criteria based on numerical models of general slopes and steep slopes. The results show that all three criteria exhibit good consistency for general slopes, but have large differences for steep slopes. It is found that tensile shearing is not considered in the yield criterion for strength reduction methods, i.e. overestimation of the tensile strength of materials is a critical cause leading to widespread disputes on the three criteria, and this inclusion is verified by calculating the safety factor of stalactites model. Therefore, the finite element strength reduction method should take equal reduction of both tensile strength index and shear strength index into consideration, so as to guarantee correctness of calculation and consistency of the three judging criteria. The strength reduction method in tensile and shearing damages has universal applicability to analysis of slope stability.%采用有限元强度折减法进行边坡稳定性分析时，边坡的安全系数在很大程度上依赖选用的失稳判别标准。通常以特征部位位移的突变性、塑性区的贯通性、数值计算的收敛性作为边坡失稳判据。然而，对这三种判据的适用性学术界一直存在不同看法。以一般边坡和陡边坡作为算例模型，对比分析三种常用的判据判定安全系数的大小。结果表明：对一般边坡三种判据有较好的一致性，陡边坡三种判据存在较大的差异。研究发现：以往用于强度折减法的屈服准则没有考虑拉伸截断，即在强度折减过程中过高的估计了材料的抗拉强度是导致三种判据对应的计算结果存在广泛争议的重要原因，并通过计算钟乳石模型的安全系数对这一结论进行验证。因此，有限元强度折减法中应考虑抗拉强度指标与抗剪强度指标同等地减少，才能保证计算结果的正确性及三种判据的一致性。考虑张拉、剪切破坏的强度折减法在边坡稳定性计算中具有普遍的适用性，是对强度折减法的改进和推动。
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