Abstract：As one of the typical disasters in the Three Gorges reservoir region，unstable rock can be classified as three types in views of unstable mode，i.e.，fall unstable rock，slide unstable rock and topple unstable rock with failure mechanism of shear，compression-shear and tension-shear respectively. Support，anchorage and filling etc. are used extensively in controlling of unstable rock in which anchorage is in most commonly used. Loads on unstable rock mass usually include weight，fissure water pressure，and earthquake force，of which fissure water pressure exists in natural condition and rainstorm condition respectively，and three load combinations are made. Taking stability safety factor that greater than 1.5 to fall unstable and topple unstable rock and 1.3 to slide unstable rock as control object，the authors establish anchorage calculation method for every type of unstable rock reinforced with anchorage and pre-stressed anchorage based on equilibrium theory and failure mechanism of every type of unstable rock.，and the minimum anchors needed can be obtained. The proposed methods have been successfully applied in control of hundreds of unstable rocks in the Three Gorges reservoir region，which will be valuable in revision of the local standard of Chongqing city.
