Objective: Traditional Chinese medicine (TCM) has been extensively used as one of popular alternative therapies for several cancers. However, it remains unclear whether TCM treatment is associated with longer survival in lung cancer patients. In this study, we explored the effect of long-term TCM treatment on patients with different stages of lung cancer. Methods: All information of lung cancer patients with stage I-III disease from January 2007 to September 2015 was collected for this retrospective cohort study. Those who were treated with TCM after surgery were divided into TCM group and the others were into the non-TCM group (control group). All patients were regularly followed up by clinic appointment or phone, and all survival data were collected from databases after the last follow-up in October 2017. Results: A total of 575 patients were included in this study, with 299 patients in the TCM group and 276 in the control group. For all patients, 5-year disease-free survival (DFS) was 62.2% in TCM group and 42.1% in the control group, and 6-year DFSs were 51.8% and 35.4%, respectively (HR = 0.51, 95% CI: 0.40 to 0.66, log-rank P <= 0.001). For patients with stage I, 5-year DFSs were 83.7% (TCM group) and 57.5% (control group) and 6-year DFSs were 73.7% and 51.9%, respectively (HR = 0.30, 95% CI: 0.18 to 0.50, log-rank P <= 0.001). For patients with stage II in the TCM group and the control group, 5-year DFSs were 59.4% and 17.6% and 6-year DFSs were 44.7% and 17.6%, respectively (HR = 0.31, 95% CI: 0.19 to 0.52, log-rank P <= 0.001), and for patients with stage III, 5-year and 6-year DFSs in the TCM group were 18.7% and 12.5% compared with 28.4% and 20.3% in the control group (HR = 1.06, 95% CI: 0.72 to 1.56, log-rank P = 0.76). Conclusions: This study demonstrated that long-term TCM treatment as an adjuvant therapy is able to improve the DFS of postoperative stage I-III lung cancer patients, especially in patients with stage I and II disease. However, these observational findings need being validated by large sample randomized controlled trials.