Abstract：Two kinds of forming models are put forward through analyzing the geological environmental conditions and the characteristics of perilous rocks. The static analytic method can be used for quantitative judgment of perilous rocks on the basis of experimental results of rock mechanics. The result shows that: the most of the perilous rocks are well stable except few ones under natural conditions; however,the perilous rocks become much unstable under the conditions of heavy rain and earthquake. The perilous rocks without steep dip cracks on their rear edges are widely distributed in the study area. The detailed study on them indicates that the perilous rocks show a poor stability when the thickness of sandstone rocks with free faces exceeds 5 m and those of limestone rocks exceeds 3 m. The stable analysis of the perilous rocks can provide evidences for the safety treatment measures of Yuntaishan scenic region.

Keyword：perilous rock;stability analysis;static analysis method;free face of rocks;