The invention relates to a preparation method of an egg yolk antibody for fowl adenovirus type 4 (FAV-4). The method comprises the following steps: (1) immunizing chickens by using an inactivated vaccine of the FAV-4, and obtaining high immune eggs; (2) collecting egg yolks, removing vitelline membranes and frena of the egg yolks, and then crushing by using a colloid mill to obtain egg yolk liquid; (3) mixing the egg yolk liquid with 0.1mol/L Tris-HCl buffer solution with a pH value of 7.2-7.4 according to a volume ratio of 1:(6-8), evenly stirring, then adding cyclodextrin with a final concentration of 1.0-2.0% (m/v) into the mixture, fully stirring, standing for 1-2h at the temperature of 4 DEG C, fully balancing, then centrifuging for 15-20min at the speed of 4000r/min under the condition that the temperature is 4 DEG C, and collecting supernatant; (4) purifying and concentrating the collected supernatant, and carrying out sterile treatment to obtain the egg yolk antibody. The egg yolk antibody, prepared by the method, for the FAV-4 is stable in properties and high in titer activity; the preparation method is suitable for large-scale preparation of the egg yolk antibody for the FAV-4.