To analyze the medication rule in herbal fumigation for knee osteoarthritis(KOA)by using Traditional Chinese Medicine Inheritance Support System v2.5(TCMISS v2.5).Methods:Herbal fumigation prescriptions for KOA from CNKI，VIP，Wanfang and PubMed database from the establishment of the databases to 2019 was collected，then the data entered into TCMISS v2.5.Analyze the frequency of application of various traditional Chinese medicinal in prescriptions，the characteristics and flavors of meridians，association rules and new prescription were analyzed.Results:Based on the analysis of 372 herbal fumigation prescriptions，it was found the top 3 most commonly used were Phryma leptostachya Linn.,Flos Carthami，Herba Lycopodii.The meridian tropism were mainly of liver，heart and spleen.The medicinal properties were mainly warm，and flavor were mainly pungent，bitter and sweet，and 11 prescriptions were found.Conclusion:Herbal fumigation for the KOA is mainly used by classic prescription Haitongpi Decoction.The method of treatment is to eliminate cold and dampness，activate blood and resolve stasis and remove obstructions in the meridians.Treating the liver is the first.The second is to take care of the heart，spleen and kidney.