Abstract: This paper presents a new method of searching for sliding surface and uses it for stability analysis of slopes reinforced with pre-tensioned cables. The reinforcement effect of cables is simplified to an external force on the bottom surface of the soil section(column) when the slice methods are used. The formula for calculating the factor of safety(FOS) is achieved in two-dimensional(2D)or three-dimensional(3D)slopes reinforced with pre-tensioned cables. Some examples are compared and analyzed. The feasibility of the proposed method is verified. Then in a certain extent, the effect on the slope stability with change of cable angle(),length of three-dimensional sliding body(L),anchorage force of cable(F) and horizontal space of reinforcement cable(S) is researched. The numerical results show the follows.(1)Cables can effectively improve the stability of slope, and can increase the range of original slope's sliding surface.(2)As the three-dimension sliding body length(L)increases, the stability of 3D slopes(including non-reinforcement slope and slopes reinforced with cables) tends to the stability of 2D slopes.(3)the greater anchorage force of per meter horizontal reinforcement spacing is,the more anchor cable's reinforcement effect on the slope is.