Abstract:Detailed investigations conducted on the rock cliff of Mogao Grottoes show that physical weathering is the major factor responsible for the deterioration of cliff rock. From the viewpoint of reinforcement engineering,weathering hazards in Mogao Grottoes are classified into 9 kinds with 3 different intensities in relation to micro- geomorgraphy. Various treatments are evaluated and suggested for engineering design;such as the PS consolidation of cliff surface,crack grouting,cable stabilization to unstable rock mass,topping of thin-covered caves and removing of unfavorable structures for stabilization constructed in the early time. The reliability of the treatments is proven and the frame structure for design of reinforcement engineering in Mogao Grottoes is established.