The utility model discloses a cave slope strengthening protection structure which is arranged on a slope of one side of a side ditch of a railroad bed, face plates or longitudinal beams are arranged on the surface layer of the slope in a paving mode, root piles are arranged from the face plates or the longitudinal beams to the underground of the slope in a drilling mode, and the root piles penetrate through a karst cave and enter a complete bed rock. Base material vegetation landscaping protection is arranged on the surfaces of the face plates or the surfaces of the longitudinal beams. The root piles and the longitudinal beams or the face plates are combined to strengthen a cave slope, integrality is good, slope safety is guaranteed, the survival rate of net base material vegetation protection plants is high, environment protection is achieved, the construction method is simple and convenient, and quality is easy to control.