Abstract: The geological structures of slopes have a great impact on the geometrical shapes of slope slips, but current stability analysis theories can not consider the influence satisfactorily. A model was provided to simulate combined slips. It divided slips into two parts, one part represented slips on which geological structures had no influence, and the other one could be affected by geological structures. Not only could it be applicable to single or multi-softening-surface, but also simulate several types of combined slips such as arc-polyline, spline-polyline and polyline-polyline, etc. All of these results were the basis of another task to search the critical combined slip. The analysis results of examples show the model is not only feasible but also practical.