The invention discloses a liquid crystal display screen, a composite substrate, and a manufacturing method. The composite substrate comprises a substrate, a carbon nano-tube layer, and an optical alignment base material. The carbon nano-tube layer is bonded on the surface of the substrate through the optical alignment base material. The carbon nano-tube layer comprises a plurality of carbon nano tubes extending along a same direction. Since the extension directions of the plurality of carbon nano tubes in the carbon nano-tube layer are the same, the carbon nano tubes arranged in parallel would form a plurality of grooves arranged in parallel. The grooves can be used for initial alignment for liquid crystal molecules, that is, the carbon nano-tube layer can be used as an alignment layer. The carbon nano-tubes have polarization effect, and have transmission effect on light whose polarization direction is vertical to the extension direction of the carbon nano tubes, and have absorption effect on light whose polarization direction is parallel to the extension direction of the carbon nano tubes, that is, the carbon nano-tube layer can be used as a polarization layer. Thus, the composite substrate can be used as an alignment layer, and also can be used as the polarization layer. Therefore, the composite substrate is used as a TFT array substrate, and is simple in structure and low in cost.