The dosage， dose and administration method of decoctions are important factors affecting the efficacy of prescriptions. By analyzing 35 decoction formulas from the Ming and Qing dynasties within the

Catalogue of Ancient Classic Famous Formulas （First Batch）

， it was found that the average dosage was equivalent to about 65 g， of which 71.4% （25/35） of the prescriptions had a dosage ≤60 g. And among them， the dosage of decoctions in the Ming dynasty was significantly smaller than that in the Qing dynasty. Considering the characteristics of formulas in Song dynasty， it is believed that decoctions in Ming and Qing dynasties were influenced by the popular use of decoctions during the Song， Jin， and Yuan dynasties. Some decoctions recorded a dosage of one dose instead of one day， which was more evident in the Ming dynasty. However， by the Qing dynasty， the usage of prescriptions with a dosage of one day gradually became more common. Therefore， in the practical research and application of classic famous formulas from the Ming and Qing dynasties， it is advised to pay attention to the difference between the dosage， one dose and the daily dosage. It is necessary to determine whether to double the dosage of the original formula based on the actual use， in order to ensure the clinical efficacy.