A flexible cover board, a manufacturing method thereof, and a display device are provided. The flexible cover board includes a flexible substrate, a buffer layer, a first hardened layer, an organic layer, and a second hardened layer. The buffer layer is disposed on a side surface of the flexible substrate, and at least one through-hole penetrating the buffer layer is filled with a nanomaterial. The first hardened layer, the organic layer, and the second hardened layer stacked in sequence are disposed on a side surface of the buffer layer away from the flexible substrate.