Objective To investigate the relationship between preoperative mean daily step counts and pulmonary complications after thoracoscopic lobectomy in elderly patients. Methods From 2018 to 2021, the elderly patients with pulmonary complications after thoracoscopic lobectomy were included. A 1∶1 propensity score matching was performed with patients without pulmonary complications. The clinical data were compared between the two groups. ResultsTotally, 100 elderly patients with pulmonary complications were enrolled, including 78 males and 22 females, aged 66.4±4.5 years. And 100 patients without pulmonary complications were matched, including 71 males and 29 females aged 66.2±5.0 years. There was no significant difference in the preoperative data between the two groups (P>0.05). Compared to the patients with pulmonary complications, the ICU stay was shorter (8.1±4.4 h vs. 12.9±7.5 h, P＜0.001), the first out-of-bed activity time was earlier (8.8±4.5 h vs. 11.2±6.1 h, P=0.002), and the tube incubation time was shorter (19.3±9.2 h vs. 22.5±9.4 h, P=0.015) in the patients wihout pulmonary complications. There was no statistical difference in other perioperative data between the two groups (P>0.05). The mean daily step counts in the pulmonary complications group were significantly less than that in the non-pulmonary complications group (4 745.5±2 190.9 steps vs. 6 821.1±2 542.0 steps, P＜0.001). The daily step counts showed an upward trend for three consecutive days in the two groups, but the difference was not significant. Conclusion The decline of preoperative mean daily step counts is related to pulmonary complications after thoracoscopic lobectomy in elderly patients. Recording daily step counts can promote preoperative active exercise training for hospitalized patients.