Abstract：According to the failure shapes of expansive soil slopes，the failure types of expansive soil slopes are sorted into three kinds，slip in surface layer，slip in shallow layer and slip in deep layer. At the same time，their formation mechanisms are also discussed. Afterwards under considering the engineering characteristics of expansive soil and the environmental factors，the shear strength of expansive soil slope is considered as the variable varied with the depth and the stability of a middle expansive soil slope in Nanyang，Henan province，China，is analysed. The distributions of the safety factors are obtained and the shallow slip character of expansive soil slope is validated. Furthermore，based on these results，the slip surfaces of three failure types are investigated. Finally，the reasonable gradient of the analysed slope and the position of shallow slip surface are put forward.
