The present disclosure provides a cover, a manufacturing method of the cover, and a display device. The cover includes a planar region and a bending region. The cover also includes a substrate, a flexible layer, and a hard layer disposed in a stack. A thickness of the substrate in the planar region is greater than a thickness of the substrate in the bending region. Decreasing the thickness of the substrate in the bending region can improve bendability of the cover, and the hard layer can ensure hardness of the planar region at a same time. Combination of the two can make the cover achieve high hardness and good bendability at the same time.