The invention discloses a traditional Chinese medicinal spray film for preventing and treating cystic acnes, and a preparation method thereof. The spray comprises main medicines purslane herb and rheum officinale, and film-forming auxiliary materials chitosan hydrochloride and PVA1788. The preparation method of the traditional Chinese medicinal spray film for preventing and treating cystic acnes comprises the following steps: (1) adding deionized water to the purslane herb, performing heating until slight boiling to carry out extraction, concentrating the obtained extract liquid until drynessto obtain purslane herb extract, and crushing the rheum officinale to form ultrafine powder; and (2) adding deionized water to the PVA1788 and chitosan hydrochloride, performing stirring in a 40 DEG Cwater bath until the PVA1788 and chitosan hydrochloride are completely dissolved, adding the purslane herb extract and ultrafine rheum officinale powder obtained in step (1), adding a modifier, performing continuous stirring to completely dissolve the purslane herb extract, the ultrafine rheum officinale powder and the modifier, adding anhydrous ethanol and deionized water to a constant volume of100 ml, and performing uniform mixing to obtain a light yellow transparent spray film solution. The traditional Chinese medicinal spray film solution for preventing and treating cystic acnes is sprayed in a mist form, and can rapidly become dry on skins to form the transparent film; and the traditional Chinese medicinal spray film has the characteristics of convenience in use, moisture-retentionand ventilation properties, and no irritation, toxic or side effects on skins.