The invention provides a liquid crystal display substrate and a preparation method thereof, belongs to the technical field of liquid crystal display, and aims at solving the problem that through holes in an existing liquid crystal display substrate causes uneven thickness of an alignment layer, so as to affect the display effect. The liquid crystal display substrate provided by the invention comprises a plurality of display structures and an alignment layer located above all the display structures; through holes are formed in at least one part of display structures; at least one part of through holes are surrounded by a baffle wall; and the baffle wall is located below the alignment layer.