The invention discloses a liquid crystal display substrate and a liquid crystal display substrate cutting device and method. The liquid crystal display substrate comprises a thin film transistor array glass substrate, a colored filter glass substrate, an external lead connector area and a black bottom layer, wherein the thin film transistor array glass substrate and the colored filter glass substrate are bonded through sealing glue, the external lead connector area is arranged on the thin film transistor array glass substrate, and the black bottom layer is arranged under the colored filter glass substrate and extends from a colored filter cutting line on the colored filter glass substrate to the external lead connector area by a preset width. Due to the fact that the black bottom layer extends from the colored filter cutting line on the colored filter glass substrate to the external lead connector area by the preset width and expands by a certain width based on the colored filter cutting line after cutting is finished to automatically detect whether black bottom layer residues exist, whether colored filter glass substrate residues exist in the external lead connector area is detected automatically without manual work, in this way, production efficiency is improved and production cost is reduced while the quality of a liquid crystal display panel is improved.