ObjectiveTo analyze medication regularity of presciptions containing Cangzhu （Atractylodes Lancea） - Huangbai （Phellodendron Amurense） based on data mining. MethodsAll the prescriptions containing Cangzhu-Huangbai in Dictionary of Chinese Medical Formulas （《中医方剂大辞典》） and the fifth edition of Chinese Pharmacopoeia （《中华医典》） were retrieved， setting up a database， counting the number of prescriptions involved， the composition of formulas in the prescriptions， the properties of the medicinal， the number of types of diseases and syndromes treated by the prescriptions， and the frequency of their appearances； drawing a network diagram of the medicinal combinations； analysing the medicinal combinations based on the association rules of the Apriori algorithm， and at the same time， analysing the association rules for the medicinal involved in the high-frequency diseases， and the core prescriptions containing Cangzhu-Huangbai pairs for specific diseases were extracted， and the medicinal in the core prescriptions were classified into four categories of raising yang and eliminating dampness， fortifying spleen and eliminating dampness， clearing dampness-heat， and specialised disease-use. ResultsA total of 323 prescriptions were identified， involving 318 Chinese herbal medicines， 52 syndromes， 200 diseases， among which arthralgia， beriberi， atrophy-flaccidity， leukorrhea， hernia-type diseases， headache， and haemorrhoids appeared more than 10 times. Through analyzing the core prescriptions for high-frequency diseases， we had four findings. Firstly， medicinal of spleen-fortifying and dampness-removing were the most frequent used in core prescriptions of Cangzhu-Huangbai pair （353 times）， and the medication mode was combination of qi-blood supplement medicinal and qi rectifying medicinal， usually using Huangqi （Astragalus mongholicus）， Renshen （Panax ginseng）， Processed Gancao （Glycyrrhiza glabra）， Baizhu （Atractylodes macrocephala）， Danggui （Levisticum officinale）， Chenpi （Citrus reticulata）， Xiangfu （Cyperus rotundus）. Then followed by the combination of heat-clearing and dampness-draining medicinal （213 times）， usually using Fangji （Stephania tetrandra）， Niuxi （Achyranthes bidentata）， and Banxia （Pinellia ternata）， and this type of heat-clearing and dampness-draining medicinal is most frequently used for haemorrhoids， and beriberi is the most frequent disease. The combination of yang-raising and dampness-removing medicinal （212 times）， often using Qianghuo （Hansenia weberbaueriana）， Chaihu （Elephantopus scaber）， Fangfeng （Carum carvi）， and this type of medicinal is most frequently used for headache， and atrophy-flaccidity is the most frequent disease. The combination of medicinal for specialised diseases was used the least frequently （39 times）. ConclusionCangzhu-Huangbai pair were often combined with medicinal of yang-raising and dampness-removing， spleen-fortifying and dampness-removing， and heat-clearing and dampness-draining to expel dampness pathogen， at the same time combined with disease-specific medicinal to treat disease and syndrome together.