The patterns of damage,causes and mechanism of the damaged roadbed in G315 road is also different from other regions,because of the characteristics of climatic conditions,topography,the geological and hydrologic geology.Based on the survey of damaged roadbed from Hongliugou to Ruoqiang across the desert, it was concluded three major damage patterns,that is "the bottom of slippery and disrepair";"erosion gnaw" and "erode section".It is generalized into physical model to research the water damage mechanism and protection project tests,so as to explore the mechanism of damaged roadbed and the protection technology in Gobi highway.Through testing and analysis and comparing with the traditional protective structure,it shows that box cabinet structure or grating cabinet structure have larger technical and economic advantages in the damaged protective works in G315 road.