For various engineering slopes, due to unloading relaxation of the rock mass or sliding disintegration of the slope, the cracks inside the slope will open by different extent, thus when measuring radon content, different parts of the slope will have different radon content anomaly. Through analyzing radon content anomaly, information as the landslide boundary and structure zoning of the slope rock mass, etc can be obtained. Landslide boundaries and rock mass structure zoning and other information can be identified because of radon anomalies analysis. Through radon anomalies analysis on two projects, landslide boundary identification and zoning on bank-slope adit rock mass structure, it has proved that radon anomalies analysis could be well used as a complementary method to provide more analysis data and thus provide objective scientific basis for slope stability study. The analysis method used is simple, easy to operate, and low in cost. In the analysis, it shall be noted that removing interference from groundwater, desiccant humidity should be excluded.