The invention relates to the technical field of display, in particular to a flexible display panel, a display device and a forming method of the flexible display panel. The flexible display panel comprises a flexible substrate, the flexible substrate is provided with a display area and a non-display area, and the non-display area is provided with a bending part; the bending part comprises a signal transmission line layer, a first covering layer and a second covering layer, the signal transmission line layer and the first covering layer are arranged in a laminated mode, and one or more grooves are formed in at least the side, away from the signal transmission line layer, of the first covering layer; the second covering layer covers the side, away from the signal transmission line layer, of the first covering layer, and the grooves are filled with the second covering layer. According to the flexible display panel, two adjacent boundary layers form a concave-convex structure, accordingly, the contact area between the first covering layer and the second covering layer is increased, the attachment force between the first covering layer and the second covering layer is improved, and accordingly the reliability of the display panel is improved.