Abstract: Four important problems in the analysis of slope stability are discussed in combination with practical engineering examples:1. Determination of potential failure surface ia two dimensional problems for limiting equilibrium analysis. An effective method for seeking failure surface is introduced which can be used for various slope engineering projects with complex geometrical and geological conditions.2. Vertical tension crack depth.3. Evaluation of stability based on calculated results of finite element method.4. The influence of seepage force on slope stability. It is pointed out that ia some cases this influence can not be ignored.