Abstract: Objective To probe into the effect of lung protective ventilation strategy (LPVS) on improving pulmonary function and occurrence of postoperative pulmonary complications (PPCS) in elderly patients undergoing laparoscopic colorectal cancer surgery. Methods The clinical data of 60 elderly patients undergoing laparoscopic colorectal cancer surgery in the First People's Hospital of Lanzhou city and Shaanxi provincial Cancer Hospital from October 2017 to October 2018 were retrospectively analyzed. Both the observation group and the control group included 30 cases. During the pneumoperitoneum period, the observation group was ventilated with VT 6 mL/kg combined with 5 cm H₂O positive end-expiratory pressure (PEEP) and received lung recruitment every 30 minutes, while the control group was ventilated with VT 6 mL/kg mode ventilation. The oxygenation indexes were recorded 1 minute after tracheal intubation (T1), establishment of artificial pneumoperitoneum 60 minutes (T3), 5 minutes before the end of operation (T4) and 10 minutes after extubation (T5). Respiratory mechanics indexes were recorded at T1, establishment of artificial pneumoperitoneum 5 minute (T2), T3, T4.The PPCs were recorded within 48 hours and 7 days after surgery. Results Compared with T1, the partial pressure of O₂ (PaO₂) values of both groups were significantly decreased at T4 and T5. Compared with control group, the PaO₂ values was significantly increased, calculated alveolar-arterial oxygen partial pressure(PA-aCO₂) was significantly decreased, whereas the oxygenation index (OI) was significantly increased in observation group at T3. T1, dynamic lung cdyniance (Cdyn) of both groups were significantly decreased and the airway peak pressure (Ppeak) of both groups were significantly increased at T2 and T3, end-tidal carbon dioxide pressure (P_ETCO₂) of control group was significantly increased at T2 and T3. Compared with control group, Cdyn was significantly increased in observation group at T2 and T3, Ppeak was significantly decreased in observation group at T2, T3 and T4. The incidence of pulmonary infection and hypoxemia in observation group was significantly lower than that in control group 48 hours after operation, and there was no significant difference in atelectasis and delayed extubation between the two groups. There was no significant difference in PPCs between the two groups on the 7 day after operation. Conclusion For elderly patients undergoing laparoscopic colorectal cancer surgery, LPVS can improve pulmonary function and significantly reduce the incidence of PPCs.