The combination proportion of Banxia （ Rhizome Pinelliae） in ZHANG Zhongjing’s formulas

measured by volume and number unit

was studied on the base of textual research on ancient and modern volume conversion standard。The method combined literature study on the species

produce places

processing with practical measurement of Banxia

and the treatment method of data statistics were applied. The results indicated that Banxia in ZHANG Zhongjing’s formulas was crude dry root of Pinellia ternata （ Thunb. ） Breit. （ family Araceae） after water washing. Half sheng of Banxia （ about 100 mL） equaled 61. 29 gram

and one piece of it was 0. 75 gram. The dosage used in ancient and modern time is different

so the dosage of Banxia should be controlled reasonably when it is used in clinic according to its combination proportion in ZHANG Zhongjing’s formulas

national pharmacopoeia and patient’s condition.