In order to improve the accuracy of the slope stability evaluation results,the TOPSIS method is applied combined with the orthogonal projection method with Euclidean distance replaced by vertical distance,the variation coefficient method is used to determine the objective weight of the index,and an improved TOPSIS-CV method is proposed.7 evaluation indexes affecting slope stability are comprehensively considered from 3 aspects:slope geometric parameters,rock mass strength parameters and external conditions,the slope stability evaluation index system is established,and the improved TOPSIS-CV model is applied to the comprehensive evaluation of slope stability of an open-pit mine.The research results show that using the vertical distance instead of the Euclidean distance,the paste progress is easier to distinguish,and the accuracy of the slope stability evaluation results is 90 %,compared with the traditional TOPSIS method,the improved TOPSIS-CV method is more accurate and can more easily comprehensively evaluate the slope stability,the improved TOPSIS-CV method has good engineering application value.