Abstract: Stability study of high-steep slope is an important research topic in surface mining.Because of the complex compose of the rock and soil mass，the uncertainty of the parameter of the rock and soil mass can not be precisely described by the traditional safety factor method.Through the rock laboratory test on the polygonal line sliding failure mode partition，strength reduction on the rock laboratory test parameter was made according to the actual situation of the rock mass in this slope engineering.At the same time，the uncertainty parameter of the rock and soil mass of the slope was described.According to the failure mode of polygonal line sliding，combing with the transfer coefficient method，the performance function for solving the non-probabilistic reliability index of the polygonal line sliding has been deduced.Combining with the different interval value，the solution of the function will be obtained，and the final non-probabilistic reliability index is got as well.From the perspective of the non-probability，the slope reliability analysis has been studied.

Key words: Slope stability, Non-probabilistic reliability, Polygonal line sliding, Interval theory