Objective:To systematically evaluate the risk factors for postoperative pulmonary complications (PPCs) in elderly patients undergoing hip fracture surgery.Methods:PubMed, Embase, Cochrance Library, CBM, CNKI and Wanfang Databases were searched.Search strategy was subject word combined with random word.The case control and cohort studies involving the influencing factors for PPCs in elderly patients undergoing hip fracture from January 2000 to November 2020 were retrieved.PPCs included pneumonia, aspiration pneumonitis, pulmonary infections, respiratory failure, atelectasis and pleural effusion, etc.The quality of literatures was assessed by using Newcastle-Ottawa Scale, data were extracted and analysis was performed using RevMan5.3 software.Results:A total of 18 studies were finally enrolled, including 15 case control studies and 3 cohort studies.The results of analysis showed that the advanced age, male, history of smoking, low body mass index, history of cerebrovascular accident, history of chronic obstructive pulmonary disease, history of diabetes, preoperative albumin concentration<35 g/L, preoperative hemoglobin concentration<120 g/L, American Society of Anesthesiologists Physical Status classification≥Ⅲ, operation delay≥48 h and general anesthesia were the risk factors for PPCs ( P<0.05). Conclusions:There are numerous risk factors for PPCs in elderly patients undergoing hip fracture surgery, and advanced age, male, history of smoking, low body mass index, history of cerebrovascular accident, history of chronic obstructive pulmonary disease, history of diabetes, preoperative albumin concentration<35 g/L, preoperative hemoglobin concentration<120 g/L, American Society of Anesthesiologists Physical Status classification≥Ⅲ, operation delay≥48 h and general anesthesia are the risk factors for PPCs in elderly patients undergoing hip fracture surgery.