Objective: To study the actual dosages of clinical prescriptions in internal medicine department of traditional Chinese medicine(TCM) based on the data from two affiliated hospital of Guiyang college of TCM

and clear the situation and characteristics of the dosage of Chinese herbal pieces in Guiyang city. Method: The methods of stratified sampling and random sampling were used to investigate 12 461 prescriptions of TCM. We constructed the database

then applied Weka KDD software to analyze. Result: We identified the frequency and clinical dosage intervals of 300 drugs

and the dosage difference between that in practice and that in the pharmacopoeia. Most of drug’s dosage centralized the 3 intervals: (3-6]

(9-12]

(12-15]

and the concrete dosages were 10

12

15

20

30 g

etc. Conclusion: The situation and characteristics of the dosages of clinical prescription in Guiyang city are coincided with the national level in internal medicine of TCM.