The invention is applicable to the technical field of ceramic membrane preparation, and provides a preparation method of a photocatalytic composite ceramic membrane. The method comprises the followingsteps: mixing ethylenediamine, boric acid, thiourea and tetrabutyl titanate sol to prepare a composite precursor; dropwise adding absolute ethyl alcohol and glacial acetic acid into the obtained composite precursor, uniformly mixing and stirring, and carrying out wet ball milling to obtain faint yellow titanium dioxide transparent sol; adding a liquid glass solution into the titanium dioxide transparent sol for dipping, wherein the dipping time is 30-50 minutes; coating a flat plate support body with the the impregnated titanium dioxide sol; placing the coated flat plate supporting body in aroom temperature environment with the humidity smaller than 40% to be stored for 12-24 h; taking out the flat plate support body, roasting in a muffle furnace by taking nitrogen as a protective gas, heating to 500 DEG C at a speed of 2-5 DEG C/min, and keeping the constant temperature for 2-8 hours; and taking out the flat plate support body from the muffle furnace, and naturally cooling to room temperature to obtain the photocatalytic composite ceramic membrane.