To analyze the compatibility regularity of Chinese patent medicine containing Hirudo to provide references for the modern clinical medication of Hirudo.Methods:Chinese patent medicine prescriptions containing Hirudo were collected from Yaozh database.The frequency of Chinese medicines,properties,flavors,meridians,main indications,and syndrome distribution of Chinese patent medicine prescriptions containing Hirudo were statistically analyzed by Excel 2010,SPSS Modeler 14.1,and SPSS Statistics 23.0.Association rule analysis and cluster analysis were performed on high-frequency drugs.Results:Fifty-nine Chinese patent medicine prescriptions containing Hirudo were obtained,with 192 drugs involved.In terms of cumulative frequency,the top 6 drugs were Hirudo,Astragali Radix,Chuanxiong Rhizoma,Salviae Miltiorrhizae Radix et Rhizoma,Angelicae Sinensis Radix,and Pheretima,which are mainly warm,cold,and plain in nature,bitter,sweet,and pungent in flavor,and act on the liver,spleen,and heart meridians,with 10 types of traditional Chinese medicine(TCM) indications(such as stroke and chest stuffiness and pains) and 14 types of primary syndromes(such as qi deficiency and blood stasis syndrome and internal obstruction of stagnant blood syndrome).Fifteen commonly used drug pairs were obtained through association rule analysis,such as Hirudo-Astragali Radix and Hirudo-Chuanxiong Rhizoma.As unraveled by cluster analysis,high-frequency drugs could be divided into three categories:blood-cooling and stasis-resolving drugs,blood stasis-breaking and expelling drugs,and qi-nourishing and stasis-expelling drugs.Conclusion:In Hirudo-containing Chinese patent medicines,Hirudo is mainly combined with tonifying drugs,blood-activating and stasis-resolving drugs,and liver-pacifying and wind-extinguishing drugs under the therapeutic principles of replenishing qi and expelling blood stasis.They are mainly used in the treatment of various cardiovascular and cerebrovascular diseases caused by blood stasis.