The invention relates to the technical field of display, in particular to a flexible display panel and a preparation method thereof. The problems of inaccurate alignment of COF bonding and FOF bondingand low yield caused by the size inhomogeneity of flexible substrate are solved. An embodiment of the present invention provides a method for manufacturing a flexible display panel, the flexible display panel comprising a display region and a bonding region, and the bonding region comprises at least two COF bonding regions. The method comprises the steps of: preparing a flexible substrate; Forming pixel units arranged in an array form on a surface of a corresponding display region of the flexible substrate; Cutting a position between at least two adjacent COF bonding regions to form a strip-like crack or hollow area, separating the at least two adjacent COF bonding regions and separating the at least two adjacent COF bonding regions structurally; affixing a back film and cutting off the back film at a position corresponding to the strip-shaped crack or the hollow area; Bonding of COF and FOF. The present invention is used to preparing the flexible display panel.