In a flexible display panel and a preparation method thereof provided by the present application, the flexible display panel includes a flexible substrate including a display area and a non-display area connected to each other, a thickness of the flexible substrate in the non-display area is less than a thickness of the flexible substrate in the display area; a thin film transistor layer disposed on one side of the flexible substrate; and an organic light-emitting layer disposed on one side of the thin film transistor layer away from the flexible substrate.