Objective To study the prognostic value of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) in newly diagnosed nasopharyngeal carcinoma patients with intensity-modulated radiotherapy (IMRT).Methods A total of 82 patients with newly diagnosed nasopharyngeal carcinoma who were admitted to our hospital from January 2016 to December 2021 were selected and all underwent IMRT. DCE-MRI was performed before IMRT, and Ktrans, Kep, Ve, and Vp were calculated. Three months after the end of IMRT, the patients were divided into good group (n = 52) and poor group (n = 30) according to the clinical efficacy. The DCE-MRI parameters before IMRT and clinical data in the good group and the poor group were compared. Logistic regression analysis was used to analyze the risk factors for poor prognosis of IMRT. The receiver operating characteristic (ROC) curve was drawn to evaluate the predictive value of DCE-MRI parameters for the prognosis of newly diagnosed nasopharyngeal carcinoma patients with IMRT.Results Compared with the good group, the Ktrans and Kep before IMRT in the poor group were significantly decreased, the proportion of anemia, the size of the primary tumor was superluminal, the T stage was T₃ to T₄, and the retropharyngeal lymph node metastasis were increased (P < 0.05). Logistic regression analysis showed that anemia [O^R = 1.732 (95% CI: 1.269, 2.194) ], the size of primary tumor was superluminal [O^R = 1.489 (95% CI: 1.254, 1.724) ], retropharyngeal lymph node metastasis [O^R = 2.659 (95% CI: 2.013, 3.305) ], T₃ or T₄ stage [O^R= 3.504 (95% CI: 1.987, 5.022) ], low Ktrans [O^R = 5.865 (95% CI: 3.145, 8.585) ], and low Kep [O^R = 3.142 (95% CI: 2.412, 3.873) ] were risk factors for poor prognosis in newly diagnosed nasopharyngeal carcinoma patients with IMRT (P < 0.05). The ROC results showed that the optimal cut-off point of Ktrans for predicting poor prognosis in newly diagnosed nasopharyngeal carcinoma patients with IMRT was 0.22 min, the AUC for predicting poor prognosis was 0.728 (95% CI: 0.618, 0.820), and the sensitivity was 80.00% (95% CI: 0.754, 0.846), the specificity was 82.69% (95% CI: 0.792, 0.862). The best cut-off point of Kep for predicting poor prognosis in newly diagnosed nasopharyngeal carcinoma patients with IMRT was 0.71 min, and the AUC for predicting poor prognosis was 0.746 (95% CI:0.637, 0.835), the sensitivity was 76.67% (95% CI: 0.698, 0.836), and the specificity was 75.00% (95% CI: 0.671, 0.829); the combined AUC of the two predicted poor prognosis was 0.762 (95% CI: 0.655, 0.849), the sensitivity was 76.67% (95% CI: 0.712, 0.821), and the specificity was 88.46% (95% CI: 0.804, 0.965).Conclusion Ktrans and Kep in DCE-MRI have certain predictive value for the prognosis of newly diagnosed nasopharyngeal carcinoma patients with IMRT, which can provide a basis for clinical individualized treatment and modification of treatment plan.