Objective To analyze the compatibility law of the herbs used in ancient prescriptions treating allergic rhinitis （AR） to provide reference for its clinical treatment today.Methods The ancient classical prescriptions treating AR were enrolled and processed with information standardization.Data mining method （frequent itemsets and association rules） was used to analyze the compatibility law of the herbs.Results Totally 101 prescriptions were studied.The result showed that those with less than 10 herbs occupied 75.25% of the total prescriptions.The herbs pungent in flavour

light in weight

and mild in smell were used in the highest frequency

of which

Xixin （Herba asari） appeared 42 times

being 41.5% of the total prescriptions.Xixin （Herba asari） and Baizhi （Radix angelicae） as a pair of herbs appeared 22 times

being the highest in frequency.Chuangxiong （Rhizoma chuanxiong）

Baizhi （Radix angelicae）

and Xixin （Herba asari） as a 3 itemset appeared 11 times

being the highest in frequency.Danggui （Angelica sinensis）

Baizhi （Radix angelicae）

Chuangxiong （Rhizoma chuanxiong）

and Xixin （Herba asari） as a 4 itemset appeared 7 times

being the highest in frequency.The analysis on association rule showed that Zisu （Purple perilla） was commonly coupled with Gancao （Radix glycyrrhizae）

Fuzi （Radix aconiti carmichaeli） with Xixin （Herba asari）

Baizhi （Radix angelicae） and Xixin （Herba asari） with Chuangxiong （Rhizoma chuanxiong）

and Qianghuo （Rhizoma seu radix notopterygii） and Fangfeng （Radix ledebouriellae） with Baizhi （Radix angelicae）.Conclusion The herbs in ancient prescriptions for AR were not many but exact in effect in treating interior and exterior and acting comprehensively on symptoms and root cause

providing a reference for its treatment nowadays.