Objective To summarize and analyze the related factors of hospital acquired pneumonia (HAP) in the elderly patients with lung cancer, and to take relevant preventive measures to improve the prognosis of the disease. Methods Retrospective analysis was carried out on 215 elderly inpatients with lung cancer in our hospital from February 2013 to July 2016. Their clinical data were collected, and univariate analysis was adapted to explore the risk factors for HAP. Results Univariate analysis revealed that male, Karnofsky performance store (KPS)<7.0, tumor node metastasis (TNM) stage, invasive operation, complication of diabetes mellitus and chronic obstructive pulmonary disease, and length of hospital stay were the risk factors for HAP in the elderly with lung cancer. Gram-negative bacteria were the main pathogens, and the infections were usually associated with fungal infection. Conclusion HAP usually results from multiple factors in the elderly with advanced lung cancer. More attention should be paid to the patients. According to the results of sputum culture, timely controlling infection is the key to improve the curative effect of them.