The invention provides a traditional Chinese medicine oral liquid for treating the infectious coryza and a preparation method of the traditional Chinese medicine oral liquid. The oral liquid per 100 ml comprises the following components by weight: 80-150g of herba laggerae as a main drug, and 0.1-0.3g of potassium sorbate or paraben esters as auxiliary materials. The invention further provides a preparation method for the traditional Chinese medicine oral liquid. The traditional Chinese medicine oral liquid is simple and convenient to take and remarkable in curative effect, has no toxic or side effects, and is suitable for the treatment of the infectious coryza, thereby solving the defects of certain Western medicines on the treatment of Haem-ophilus paragallinarum; besides, the infectious coryza is treated by the Chinese herbal medicine, so that the effects of low drug residues and low toxic or side effects are achieved, and the requirements for sustainable poultry industry development, the improvement of people's life quality, and the consumption of green food can be met.