Preparation method of chicken feed additive

The invention discloses a preparation method of a chicken feed additive, wherein the raw materials of the chicken feed additive are as follows: 10 to 30 parts of chitosan, 10 to 30 parts of xylo-oligosaccharide, 3 to 6 parts of indigowoad leaf extract, 8 to 10 parts of dandelion extract and 8 to 10 parts of liquorice extract; the preparation method comprises the following steps of: extracting thedandelion extract, the liquorice extract and the indigowoad leaf extract respectively, and then mixing the extracts with the xylo-oligosaccharide uniformly to obtain the chicken feed additive. The chicken feed additive disclosed by the invention can be used for efficiently increasing the laying rate of hens and enhancing the immunity of the chicken; antibiotics are not needed, so that the production of green pollution-free eggs is facilitated.