Abstract: Focusing on some basic problems in stability evaluation of the sliding surface with tension cracks, the feasibility and adaptability of the two kinds of confusing "ignoring" methods are analyzed through over a thousand examples, and their effects on the stability of sliding surfaces with tension cracks are also investigated under different depths of tension cracks, different geometric shapes of sliding surfaces (arc, polyline, combination), different methods of safety factor. The main conclusions are drawn as follows: (1) When the tension cracks are not filled with water, the first kind of method is only applicable to the simplified Janbu and Bishop methods, but not to GLE and unbalanced thrust methods. Also, the first kind of method does not work when the water pressure is applied, only the second kind of method works. (2) The curve of the safety factor with tension cracks is related to whether the inter-slice force before cracks happen is tension or pressure, which is also related to the soil cohesion, depth of the tension cracks and methods of safety factor. If the cohesion is low, the inter-slice force is more likely to be pressure, and if the cohesion is high, the inter-slice force is more likely to be tension. (3) It's conducive to the convergence of the iterative solution by setting tension cracks in analysis, especially for the strict methods, such as GLE. The research results may provide a solid theoretical and feasible analysis method for scientifically evaluating the stability of the sliding surfaces with tension cracks.