Abstract: Objective To investigate the effect of threedimensional conformal radiotherapy（3D-CRT） and intensitymodulated radiotherapy（IMRT） on radiationinduced lung injury（RILI） and their relations with parameters of dose volume histograms（DVH）. Methods One hundred and fifty-one cases of locally advanced lung cancer patients treated with chemoradiotherapy from single clinical center were enrolled retrospectively， including 90 cases of 3D-CRT and 61 cases of IMRT. All patients were treated with radical radiotherapy dose， 1.8-2.0Gy per fraction， 5 fracions one week， and the median prescribed dose was 60.0Gy. RILI was defined according to the National Cancer Institute Common Toxicity Criteria， version 30. The incidence of RILI in two groups was calculated and its association with the parameters of DVH were analyzed. Results The incidence of RILI（≥grade 2） in 3D-CRT group was lower than that in IMRT group（17.8％ vs. 24.6％）； on the contrary， the incidence of RILI（≥grade 3） in 3DCRT group was higher than that in IMRT group（8.9％ vs. 3.3％）. However， there was no statistically significant difference（P＞0.05）. In 3D-CRT group， V20 would increase the risk of RILI（OR=3.780, P=0.030）， whereas， in IMRT group， V5， V10， V13， V20 and mean lung dose would increase the risk of the RILI（OR=3.575-6.286, P=0.003-0.045） by univariate analysis. Multivariate analysis confirmed V20 was an independent risk factor. Conclusion 3D-CRT and IMRT seemed to have no significant effect on RILI（≥grade 2）， and V20 is tightly correlated with RILI.