Objective To investigate the value of ADC value in predicting the treatment sensitivity of nasopharyngeal carcinoma (NPC). Methods 142 cases of NPC were performed MR diffusion weighted imaging, and the ADC values of primary foci were obtained. According to the treatment results, these cases were divided to sensitive group (104 cases) and resistance group (38 cases). To analyze the relationship among groups, ADC values and T staging, estimate the value of ADC value in predicting the treatment sensitivity through the Az value of ROC curve. Results The ADC vales of T1 (0.818±0.111)×10-3mm2 /s, T2 (0.756±0.169)×10-3mm2 /s, T3 (0.684±0.119)×10- 3 mm2 /s and T4 (0.667±0.093)×10-3mm2 /s were significantly different on the whole (F=6.595, P=0.000). The ADC value of the sensitive group (747±0.141)10-3mm2 /s was greater than that in the resistance group (0.658±0.129)×10-3mm2 /s, (t=3.421, P=0.001). In sensitive group, T1 (0.822±0.114)×10-3mm2 /s, T2 (0.773±0.161)×10-3mm2 /s, T3 (0.697±0.114)×10-3mm2 /s and T4 (0.747±0.091)×10-3mm2 /s were significantly different on the whole (F=3.945, P=0.010). In resistance group, T1 and T4 were not significantly different on the whole. Conclusion ADC value is closely related to treatment sensitivity and T staging, which can be an effective method for predicting the treatment effect of nasopharyngeal carcinoma. The therapeutic sensitivity of NPC increased with the increase of ADC values.