Objective To analyze the medication law of medical records of Pi-dan constraint heat stage in the book New Discussion on Pi-dan（脾瘅）: Understanding and Treatment of Metabolic Syndrome in Traditional Chinese Medicine（abbreviated as "New Discussion on Pi-dan"）. Methods The medical cases recorded in the book New Discussion on Pi-dan which were at Pi-dan constraint heat stage from January 2004 to December 2016 were included

and data on patients′ basic information

clinical symptoms

laboratory examination

diagnosis of traditional Chinese and western medicine

treatment and prescription were collected. Epidata 3.1 software was used to establish the database of the medical records. The Apriori algorithm provided by SPSS Modeler 14.2 software was used to analyze association rules of drug-drug

drug-symptom and drug-western medicine indicators relationships. Results A total of 79 medical records were included involving 27 syndromes; the top three syndromes with frequency ≥3 times were liver-stomach constraint heat pattern

binding of phlegm and heat pattern

internal accumulation of ointment-turbidity pattern

middle jiao（焦） obstruction and stagnation pattern

and accumulations and gatherings of ointment-turbidity pattern. There were 20 treatment methods

of which the top three methods with frequency ≥3 times were dispersing ointment and directing turbidity downward

using acridity to open and bitterness to discharge

clearing heat and draining turbidity

moving stagnation and unblocking collaterals

clearing constraint heat

and invigorating blood and unblocking collaterals. There were 79 formulas

and the top three prescriptions with frequency ≥3 times included Modified Xiaoxianxiong Decoction（小陷胸汤加减）

Modified Dachaihu Decoction（大柴胡汤加减） and Modified Dahuang Huanglian Xiexin Decoction（大黄黄连泻心汤加减）. Ninety-eight common herbs were involved with a total frequency of 792 times. The five most frequently used herbs with frequency ≥15 times were Haunglian（Rhizoma Coptidis）

Huangqin（Radix Scutellariae）

Qing Banxia（Rhizoma Pinelliae Concisum）

Shengjiang（Rhizoma Zingiberis Recens） and Sheng Dahuang（Radix et Rhizoma Rhei）. According to the drug-drug association rules with support degree ≥15% and confidence degree =100%

the most important association at different stages were "Ganjiang(Rhizoma Zingiberis→Huanglian"

"Gualouren（Semen Trichosanthis） + Qing Banxia→Huanglian"

and "Sheng Shanzha（Fructus Crataegi） + Gualouren + Qing Banxia→Huangliuan". According to the support degree ≥5% and confidence degree =100%

the most important drug-symptom association at different stages were "Huanglian-deep and slippery pulse"

"Shuizhifen（Hirudo） + Ganjiang→insomnia"

"Shuizhifen + Ganjiang + Huanglian→insomnia "

and "Hongqu（Fermentum Rubrum） + Zhimu（Rhizoma Anemarrhenae） + Qing Banxia + Huanglian→fatigue". According to the support degree ≥5% and confidence degree =100%

the important drug & western medicine indicator association rules were "Huanglian→2 h-PG"

"Cangzhu（Rhizoma Atractylodis） + Huanglian→glycosylated hemoglobin"

"Chishao（Radix Paeoniae Rubra） + Haungqin + Huanglian→glycosylated hemoglobin"

and "Cangzhu + Tianhuafen（Radix Trichosanthis） + Chishao + Ganjiang→glycosylated hemoglobin". Conclusion The syndrome differentiation method of "state and target" is used in the Pi-dan constraint heat stage. The drug combination is characterized by "minor formula" target to patients′ symptoms and signs（symptom target） and western medicine indicators（indicator target）.