This study on right side roadbed slope (No.2 Zhu-gen mountain) project relies on K33+020~K33+240 of Xiao-Long highway in mountain areas of eastern Yunnan province. Research focus on cataclastic rock slope stability of highway reconstruction project and strength degradation of saturated cataclastic rock. With sandstone sampling by ultrasonic-rebound combined method, mechanical and deformation behavior of natural samples and saturated samples were tested by the dynamic tri-axial instrument of MTS815.04. On the factors of experimented data, field data and field condition, numerical simulation analysis on slope stability by MIDAS was took. Results shows that factors of saturated samples as compressive strength decreased 31.12%, cohesion decreased 22.47%, angle of internal friction decreased 28.57% and elastic module decreased 28.98%, for which is water-sensitive rock. Slope safe factor on natural state was 1.7625 and on saturated state was 0.5125 after excavating, which demonstrates that slope was stable on natural state and unstable on saturated state. The results provide guidance for slope protection and construction.