The invention provides a preparation method of a composite ceramic microfiltration membrane. The preparation method comprises the following steps of: mixing and dissolving polyethylene oxide and deionized water, adding mullite powder, modified attapulgite and carboxymethyl cellulose, carrying out ball milling to obtain mixed slurry; dropping polyacrylic acid, regulating the pH value and stirring;slowly adding boehmite sol and titanium dioxide sol; fast dewatering, taking out wet mud cakes and drying; grinding, granulating, sieving and taking powder; carrying out dry-pressing molding on the powder, and carrying out isostatic pressing molding; calcining to obtain a supporting body; mixing the mullite powder and the modified attapulgite with the boehmite sol and the titanium dioxide sol to obtain suspension; mixing and dissolving the polyanionic cellulose, polyethylene oxide and the deionized water, adding into the suspension, evaporating and quantifying, carrying out vacuum defoaming and obtaining membrane coating liquid; dipping a supporting body into the membrane coating liquid, drying, then sintering and naturally cooling. The composite ceramic microfiltration membrane prepared by the preparation method has the beneficial effects that the average hole diameter of the microfiltration membrane is 0.273-0.276mu m, the pure-water flux is high and the intercepting effect is very good.