A directional optical waveguide, a directional backlight module, and a display device are provided, which relate to the field of stereoscopic display, to resolve a problem that a stereoscopic display pixel resolution R 3D of the display device applying a wave optical directional backlight stereoscopic display technology is low. The directional optical waveguide (1) includes a time division multiplexing unit (3) and N layers of optical waveguides (1N1) that have a same light-emitting direction and that are stacked, a light-emitting surface of each layer of optical waveguide (1N1) being provided with a pixel-type grating (1N2); the time division multiplexing unit (3) being configured to hierarchically control, within each frame video stream cycle, the N layers of optical waveguides (1N1) to introduce a source light ray into a corresponding pixel-type grating (1N2) during a corresponding frame video period, and the source light ray that is introduced into the pixel-type grating (1N2) being diffracted in the pixel-type grating (1N2) to form a plurality of first-order diffraction light rays that have different diffraction angles and diffraction azimuth angles and are in a one-to-one correspondence with display pixels, to be incident on a next layer of optical waveguides (1N1). The directional backlight module includes the directional optical waveguide (1). The directional optical waveguide (1) is used in the display device.