Objective To observe the effect of intravenous injection of lidocaine on lung injury caused by lower ischemia‑reperfusion in elderly patients with hypertension. Methods Elderly patients with hypertension who were scheduled for unilateral knee replacement from June 2021 to June 2022 were selected. All the patients finished surgery under general anesthesia. According to the random number table method, they were divided into two groups (n=30): a control group (group C) and a lidocaine group (group L). Group L was intravenously injected with lidocaine at 1.5 mg/kg for anesthesia induction followed by intravenous infusion at 2 mg·kg−1·h−1, until the tourniquet was deflated. Meanwhile, group C was administered with the same volume of normal saline. Then, 1 ml of arterial blood was drawn via the radial artery before operation (T0), 1 min after deflation of the tourniquet (T1), and 1 h after surgery (T2). Blood gas analysis was used to detect the arterial blood partial oxygen pressure (PaO2), carbon dioxide partial pressure (PaCO2), and to calculate respiratory index (RI), oxygenation index (OI), and the difference of alveoli‑arterial oxygen pressure (PA‑aDO2). The OI was used to evaluate the presence of lung injury. The number of lung injury cases was recorded at each time point. The changes of blood pressure, heart rate, pulse oxygen saturation (SpO2), and end‑tidal carbon dioxide partial pressure (PETCO2) were recorded. Results Compared with group C, patients in group L showed statistical differences in PaO2, PaCO2, PA‑aDO2, RI, and OI at T1 and T2 (P<0.05), where group L presented increases in PaO2 and OI, as well as decreases in PaCO2, PA‑aDO2, and RI, compared with group C. Compared with group L, a significant increased number of lung injury cases were observed in group C (P<0.05). The changes of vital signs (blood pressure, PETCO2, heart rate and SpO2) in group C were more obviously than those in group L (P<0.05). Conclusions Intravenous infusion of lidocaine can relieve lung injury caused by lower ischemia and reperfusion in elderly patients with hypertension due to tourniquet use, and improve the lung function.