Objective To study the rules of symptoms, patterns, and medicines of medical records of lung distention treated by Xin'an doctors through data mining methods, and to explore the characteristics of Xin'an doctors in the treatment of lung distention. Methods Medical records related to the treatment of lung distention by Xin'an doctors were collected and sorted from the medical books of Xin'an. After the standardized processing of various information, mathematical models such as frequency analysis, topology analysis, Louvain clustering, and factor analysis were used to conduct data mining research on symptoms, patterns, and prescriptions. Results We included 361 medical records and counted 272 traditional Chinese medicines in total. Among them, 35 were core medicines, including Poria, Radix Glycyrrhizae, Semen Armeniacae Amarum, Semen Coicis, Rhizoma Pinelliae, Radix Ginseng, Rhizoma Atractylodis Macrocephalae, and Fructus Schisandrae Chinensis. In the lung distention, clinical practice of Xin'an doctors, tonic medicines (30.14%) were used most, followed by expectorant cough suppressants and anti-asthmatic medicines (22.81%). The pattern of phlegm and dampness accumulating in the lung (30.19%) was the most commonly observed, and the patterns of deficiency were mainly lung qi deficiency (22.44%), spleen qi deficiency (21.05%), and kidney qi deficiency (17.45%). Semen Armeniacae Amarum, Poria, Semen Coicis, Rhizoma Pinelliae, and Exocarpium Citri Grandis were the core prescription medicines for the pattern of phlegm and dampness accumulating in the lung. Poria, Radix Glycyrrhizae, Radix Ginseng, Rhizoma Atractylodis Macrocephalae, Semen Armeniacae Amarum, and Pericarpium Citri Reticulatae were the core prescription medicines of the lung qi deficiency pattern. Poria, Radix Ginseng, Radix Glycyrrhizae, Rhizoma Atractylodis Macrocephalae, Pericarpium Citri Reticulatae, and Rhizoma Pinelliae were the core prescription medicines of the spleen qi deficiency pattern. Poria, Rhizoma Dioscoreae, Radix Rehmanniae Preparata, Fructus Corni, and Fructus Schisandrae Chinensis were the core prescription medicines of the kidney qi deficiency pattern. Furthermore, 10 common factors were extracted by factor analysis. The disease's main locations were the lung, spleen, and kidney. Water dampness, phlegm, and blood stasis were the main pathological factors. Conclusion Lung distention is a disease whose pathogenesis is the root deficiency with the branch in excess. The deficiency of the lung, spleen, and kidney are the root, while the pathological factors of phlegm, blood stasis, and heat are its branch. In Xin'an doctors' clinical practice, they preferred to use Poria, Semen Coicis, Radix Ginseng, and Rhizoma Atractylodis Macrocephalae to treat lung distention. While eliminating phlegm, clearing the lung, relieving cough, and relieving asthma were used to correct the obvious and superficial pathological factors of lung distention, these were often combined with medicines for tonifying the lung and kidney as well as strengthening the spleen to benefit the root cause. [ABSTRACT FROM AUTHOR]