Application of pharmaceutical composition to prevention and treatment of infectious bronchitis of chicken

The invention discloses an application of a pharmaceutical composition to prevention and treatment of infectious bronchitis of chicken. The pharmaceutical composition is prepared from 17-51 parts of Berberis dictyophylla, 6-18 parts of Saxifraga unguiculata, 9-27 parts of Sorbus pohuashanensis bark, and 15-45 parts of Breynia fruticose; a preparation method of the composition comprises the following steps: mixing and soaking the Berberis dictyophylla, the Saxifraga unguiculata, the Sorbus pohuashanensis bark and the Breynia fruticose, and decocting for 2-3 times, combining the decoctions and concentrating to thick, adjusting the alcohol concentration to 60-70% through ethanol, performing precipitating and filtering, and adding the ethanol in the concentrated medicine liquor to adjust the alcohol concentration to 75%-80%, performing precipitating and filtering, concentrating the filtrate, adding water to refrigerate and precipitate, filtering and concentrating. The pharmaceutical composition is used for prepar