Objective To summarize medication rule in Guizhi Decoction（ 桂枝汤） in the ancient and modern consilias. Methods Collect consilias that explicitly use Guizhi Decoction. Then they normatively processed information about amount and dosage of herbs brought into consilias and set up a database. Used descriptive statistical method to make frequency analysis about primary herbs in Guizhi Decoction

category of modified herbs

dosage of common modified herbs

case of uniting prescription. Made statistics about average

minimum

maximum and mode of dosage of primary Guizhi Decoction and used association rules to make correlation analysis between modified herbs and primary symptom. Results There were 1035 consilias included. Clinical common dosage of each herb in Guizhi Decoction includes: Guizhi（ Cassia Twig） 10 g

Baishao（ Radix Paeoniae albae） 10 g [or Chishao（ Radix Paeoniae rubrae） 15 g]

Shengjiang（ Rhizoma Zingiberis recens） 10 g or 3 pieces [or Ganjiang（ Rhizoma Zingiberis）15 g

baked ginger 3 g]

Dazao（ Fructus Zizyphi jujubae） 5 g or 5 grains and Gancao（ Radix Glycyrrhizae） 6 g.There were 229 herbs used to modify Guizhi Decoction

2481 times in total. Occurrence frequency of the top five herbs were Huangqi（ Radix Astragali）（ 181）

Danggui（ Radix Angelicae sinensis）（ 144）

Fangfeng（ Radix Ledebouriellae）（ 141）

Baizhu（ Rhizoma Atractylodis macrocephalae）（ 137）

Dangshen（ Radix Codonopsis）（ 128）. Involved herbs category among the top five were medicines for tonifying deficiency（ 743）

medicines for relieving exterior syndrome（ 399）

medicines for heat-clearing（ 181）

medicines for invigorating blood circulation and eliminating stasis（ 155） and medicines for tranquilization（ 146）. There were 47 uniting prescription used 90 times. The uniting prescription of frequency more than 2 times were Yupingfeng San（ 玉屏风散

29）

Danggui Buxue decoction（ 当归补血汤

5）

Shengmai Yin（ 生脉饮

4）

Siwu decoction（ 四物汤

3）

and Mahuang Fuzi Xixin decoction（ 麻黄附子细辛汤

3）. Conclusion Clinical dosage of Guizhi Decoction has no obvious difference with the primary. The most modified herb is for tonifying deficiency. In the prescription

Shengjiang（ Rhizoma Zingiberis recens）

Dazao（ Fructus Zizyphi jujubae）

Gancao（ Radix Glycyrrhizae） are important component herbs that are not pruned optionally.