Provided is a flexible display screen, including: a flexible substrate provided with a foldable portion; pixel units disposed on a first surface of the flexible substrate; and a fold detection device including a reflective grating structure, an optical waveguide structure and a photoelectric sensor, wherein the optical waveguide structure and the reflective grating structure are sequentially laminated on the first surface of the flexible substrate and both disposed in the foldable portion, an orthographic projection of the optical waveguide structure onto the flexible substrate is overlapped with an orthographic projection of the reflective grating structure onto the flexible substrate, and the optical waveguide structure is connected to the photoelectric sensor.