Objective:To summarize the prescriptions and medication rules of Qianjin Fang (Essentially Treasured prescriptions) for treating low back pain based on the software of traditional Chinese medicine inheritance assistance system. MethodsThe prescriptions for the treatment of low back pain in Qianjin Fang were sorted out and the usage frequency of various Chinese herb medicines in the prescriptions and the association rules among Chinese herb medicines were analyzed by unsupervised data mining methods such as apriori algorithm of association rules and entropy clustering of complex system.  Results:A total of 38 prescriptions were selected and the Chinese herb medicines used frequently in the top 5 were Rougui (Cortex Cinnamomi), Gancao (Radix Glycyrrhizae), Duzhong (Cortex Eucommiae), Fuling (Poria), Danggui (Radix Angelicae Sinensis); 14 core combinations of Chinese herb medicines and 7 new candidate drug groups were extracted.  Conclusion:The prescriptions for low back pain in Qianjin Fang mostly have the functions of tonifying and purging, simultaneously regulating qi and blood, and focus on warming yang to dissipate cold, promoting qi flow to activate blood, tonifying the liver and kidney, invigorating qi to promote urination and dispelling wind to relieve exterior syndrome.