The invention provides a composition for skin allergy and impaired skin barrier and a preparation method thereof. The composition comprises the following components by weight percent: 8-12% of purslane extract, 3-7% of gentina root extract, 3-7% of sophora root extract, 3-7% of snowparsley extract, 3-7% of asiaticoside, 1-5% of densefruit pittany root-bark extract, 0.5-1.5% of artesunate, 1-3% oflicorice extract, 0.5-1.5% of ceramide, 0.3-0.9% of cholesterol, 0.2-0.6% of fatty acid, 15-27% of butanediol and 35-47% of deionized water. The composition disclosed by the invention mainly adopts traditional Chinese medicine components, is safe and effective, and has the effects of calming and relieving itching, relieving heat and diminishing inflammation and reducing swelling and removing dampness for facial allergy, hormone dependent dermatitis, acne rosacea and the like; and meanwhile, due to long-term use, the composition can achieve the effects of gradually improving erythema and desquamation, promoting keratinized cell differentiation maturation and repairing skin barrier to stabilize.