This paper proposes a digital design method of subgrade slope protection, which constructs a slope protection knowledge base by referring to the design experience of several highways and national and provincial trunk roads, integrates the design data of routes, topography, geology and other multi-source design data. Under the practice above, the paper realizes the slope protection design and engineering quantity calculation through intelligent analysis means, and forms a standardized design result. It is proved that this method can effectively reduce the repetitive work of designers and improve the design efficiency and design quality, which could be a reference for the digital and intelligent design of roadbed engineering.