OBJECTIVE: To explore the correlation between dose volume histogram (DVH) parameters and lung function changes before and after radiotherapy and the occurrence of radiation-induced lung injury (RILI), and to evaluate its value in predicting the risk of RILI. METHODS: 120 patients with advanced non-small cell lung cancer diagnosed in Jiaozhou Central Hospital of Qingdao City in the past three years and received chest conformal (intensity modulated) radiation therapy were selected. Before radiotherapy, irradiation of 45-50 Gy, and 1 month after radiotherapy, the patients were tested for lung function. The evaluation of radiation lung injury was based on the RTOG acute radiation lung injury classification standard, and the observation end point was ≥2 grade RILI. RESULTS: There are 34 patients with ≥2 grade RILI among all enrolled patients, including 23 cases of grade 2 and 11 cases of grade 3. The difference between FVC, FEV1, FEV1 / FVC, DLCO, V5, V10, V15 before radiotherapy, 45-50 Gy, and 1 month after radiotherapy were statistically significant (P <0.05). The lung function, V5, V10, and V15 before radiotherapy were related factors for RILI (P <0.05). And the risk of RILI was 1.855 times that of patients with higher FEV1 / FVC before radiation therapy (OR = 1.855 (1.199-1.946)), patients with V10 ≥50% were 3.673 times higher than patients with V10 <50% (OR = 3.673(1.548-7.582)). CONCLUSIONS: V10≥50% and FEV1 / FVC are high-risk factors for RILI before radiotherapy, which has certain value in predicting the risk of RILI.