To investigate the risk factors for lung infection in lung cancer patients undergoing radiotherapy.We selected 142 patients with lung cancer who underwent radiotherapy at our hospital from January 2020 to June 2021. The patients were divided into groups according to whether they had pulmonary infection during radiotherapy in our hospital, which was infected group (n=44) and the uninfected group (n=98), respectively. To observe the incidence of lung infection in lung cancer patients during radiotherapy. The distribution of pathogenic bacteria in patients with pulmonary infection was observed. Clinical data of the two groups were collected and compared. The risk factors of lung cancer patients complicated with lung infection were analyzed by binary Logistic regression.All patients with lung cancer complicated with lung infection underwent relevant examination, and the results showed that they were all complicated infections, and the composition ratio of Klebsiella pneumoniae was the highest (31.82%), followed by Staphylococcus, Pseudomonas, and fungi, which accounted for 27.27%, 22.73%, and 18.18%, respectively. Binary Logistic regression analysis showed that age ≥60 years old, smoking history ≥30 years, radiotherapy duration of combined drug regimen > 2 weeks, pathogenic bacteria combined infection, albumin content < 30 g/L were risk factors for lung cancer patients during radiotherapy.Age ≥60 years old, smoking history ≥30 years old, radiotherapy duration of combined drug regimen > 2 weeks, pathogenic bacteria combined infection, albumin content < 30 g/L are the risk factors for lung cancer patients during radiotherapy. Clinical prevention and intervention should be based on the aforementioned independent risk factors to decrease the incidence of lung infections, thereby enhancing patient prognosis.