Objective: To study the value of MR 1.5T diffusion weighted imaging (DWI) in the evaluation of cervical lymph node metastasis in nasopharyngeal carcinoma (NPC). Methods: 37 cases of benign lymph node enlargement and 15 patients with nasopharyngeal carcinoma were examined by routine MR and multi DWI b, and the quality of DWI images with different b values were compared. ADC curves of benign and malignant lymph nodes with different b values were recorded. The ROC curves were recorded. Results: Avanto nasopharynx deformation small, the image background is suppressed sufficiently and artifacts less, better contrast with surrounding soft tissue and lesion and lymph node showed clearly; nasopharyngeal carcinoma and benign lymph nodes and neck metastasis lymph node of ADC value along with the increasing of b value showed a downward trend, 8 kinds of b value metastasis lymph nodes in nasopharyngeal carcinoma and primary tumor to the comparison, the difference of the ADC values of no statistical difference (P>0.05). The benign lymph nodes and metastatic lymph nodes were compared, ADC values were statistically different (P<0.05); b=800 s/mm2 was the best for the identification of benign and malignant lymph nodes, the sensitivity was 100%, specificity was 83.2%. Conclusion: 1.5T MR diffusion weighted imaging (DWI) technology can effective identification of lymph nodes, when b=800 s/mm2, DWI images has good quality, and the diagnosis of benign and malignant lymph nodes effect best, it is worth widely applying in the diagnosis of cervical lymph node metastasis of nasopharyngeal carcinoma (NPC).