Abstract: In order to further study the stability of the dangerous rock mass of a project and reduce the impact and harm of the project implementation on the main works，taking the dangerous rock on the left side of Sangshuping Bridge of Jiuzhaigou Mianyang Expressway as the engineering background，on the ba⁃ sis of studying the slope shape，characteristics and failure mechanism of the dangerous rock mass，the overall stability of the dangerous rock mass is qualitatively analyzed and quantitatively calculated. Accord⁃ ing to the stability calculation results，considering that the stress compensation of the excavated natural slope is required under the rainstorm condition，the treatment scheme of "slope anchoring + column plate retaining wall embedding + rib column anchor cable reinforcement" is proposed to reinforce the bottom of the boulder dangerous rock body based on the sliding failure mode. After the implementation of the scheme，the effect is remarkable，the stability of the dangerous rock body is good，and the risk of the bridge project below is effectively reduced.

Key words: dangerous rock mass, stability analysis, treatment measures