The present application provides a foldable display device, a manufacturing method thereof, and a jig. The foldable display device includes a folding region, a non-folding region, a flexible display panel, and a functional layer attached through an adhesive layer. In a pre-bent state of the foldable display device, an angle between portions of the foldable display device corresponding to the non-folding region on two opposite sides of the folding region is greater than 0 degree and less than 180 degrees. A stress of a portion of the adhesive layer corresponding to the folding region is less than or equal to a first predetermined threshold.