Objective To explore the clinical significance of EBV-DNA quantitative detection in patients with recurrence and metastasis of nasopharyngeal carcinoma after radiotherapy.Methods A total of 60 patients with nasopharyngeal carci noma treated in Ji′an Central People′s Hospital from January to November 2019 were selected as the research objects.According to the curative effect after radiotherapy, they were divided into three groups：continuous remission group (38 cases), local recurrence group (13 cases) and distant metastasis group (9 cases).EBV-DNA gene copies in whole blood were detected by PCR in all patients.The positive detection rate of EBV-DNA and the copy number of EBV-DNA were compared among the three groups, and the changes of EBV-DNA copies before and after the second treatment were further compared.Results The positive detection rate of EBV-DNA and the copy number of EBV-DNA in the local recurrence group and the distant metastasis group were higher than those in the continuous remission group, and the differences were statistically significant (P＜0.05);the positive detection rate of EBV-DNA and the copy number of EBV-DNA in the local recurrence group and the distant metastasis group were not significantly differents(P＞0.05);the copy number of EBV-DNA in the local recurrence group and the distant metastasis group after treatment were lower than those before treatment, the difference was statistically significant (P＜0.05).There were no significant differences in the number of EBV-DNA copies between local recurrence group and distant metastasis group before and after treatment (P＞0.05).Conclusion There are significant differences in the results of quantitative detection of plasma EBV-DNA in patients with different radiotherapy prognosis.Quantitative detection of plasma EBV-DNA can be used as a reliable tumor marker to monitor the recurrence and metastasis of nasopharyngeal carcinoma after radiotherapy.