The invention discloses a preparation method of a moisture-proof traditional Chinese medicine coated film, which relates to a coating technology of the traditional Chinese medicine and belongs to the medicinal preparation field. The moisture-proof traditional Chinese medicine coated film comprises the following components: 30-40 parts of hydroxypropyl methyl cellulose, 5-8 parts of triethyl citrate, 6-10 parts of xylitol, 4-8 parts of castor oil, 4-8 parts of tween-80, 14-18 parts of dextrin, 6-10 parts of aerosol, 6-10 parts of zein, 5-10 parts of 1% of artificial food coloring solution, 350-420 parts of distilled water (40-50 DEG C) and balance of ethanol with 95% of concentration; wherein weight unit of solid is gram, and volume unit of liquid is milliliter. The moisture-proof traditional Chinese medicine coated film has the beneficial effect of stable chemical property of a film forming substance, inertia to an enzyme system, no physiological toxicity and no usage of cane sugar; the coated film has the advantages of moisture resistance, heat resistance, cold resistance and abrasion resistance which are better than that of the sugar coated tablets, so that the stability of the coated film is increased, and storage period is prolonged.