Abstract: Slope instability is the result of the continuous evolution of the interaction of geological environment conditions in a certain area, so many factors should be considered when evaluating the stability of a slope. In this paper, the influence factors and evaluation methods of Xiashu loess slope stability in Zhenjiang are taken as the main research objects. Using the attribute reduction of rough set theory, six influencing factors are obtained. The influence degree, importance degree and weight value of influencing factors interaction on slope stability are received by establishing an interaction matrix of influencing factors. Finally, the evaluation index and quantitative standard of slope stability were established, and the calculation method of SII index and the corresponding slope stability classification were determined. As a result, a comprehensive evaluation method for the stability of the Xiashu loess slope in Zhenjiang area is developed, which provide a basis for the slope stability evaluation in this area.