The prescriptions including Polygoni Multiflori Caulis that built by Pro. Yan were collected to build a database based on traditional Chinese medicine (TCM) inheritance assist system. The method of association rules with apriori algorithm was used to achieve frequency of single medicine, frequency of drug combinations, association rules between drugs and core drug combinations. The datamining results indicated that in the prescriptions that including Polygoni Multiflori Caulis, the highest frequency used drugs were parched Ziziphi Spinosae Semen, Ostreae Concha, Ossis Mastodi Fossilia, Salviae Miltiorrhizae Radix Et Rhizoma, Paeoniae Rubra Radix, and so on. The most frequent drug combinations were "Polygoni Multiflori Caulis-parched Ziziphi Spinosae Semen", "Ostreae Concha-Polygoni Multiflori Caulis", and "Polygoni Multiflori Caulis-Ossis Mastodi Fossilia". The drug association rules of confidence coefficient 1 were "Ostreae Concha-->Polygoni Multiflori Caulis", "Poria-->Polygoni Multiflori Caulis", "parched Ziziphi Spinosae Semen-->Polygoni Multiflori Caulis", and "Paeoniae Alba Radix-->Polygoni Multiflori Caulis". The core drug combinations in the treatment of insomnia were Ossis Mastodi Fossilia, Polygoni Multiflori Caulis, Salviae Miltiorrhizae Radix et Rhizoma, Ostreae Concha, Polygalae Radix, Margaritifera Concha, Poria, and parched Ziziphi Spinosae Semen. And the core drug combinations in the treatment of obstruction of Qi in chest were Salviae Miltiorrhizae Radix Et Rhizoma, Polygoni Multiflori Caulis, parched Ziziphi Spinosae Semen, Trichosanthis Fructus, Allii Macrostemonis Bulbus, and Paeoniae Rubra Radix.