In locally advanced nasopharyngeal carcinoma(NPC), although radiotherapy and chemotherapy has been given, patients still locally recurrence and distant metastasis. There is no standard treatment recommendation for metastatic NPC who failed to chemoradiotherapy therapy. Apatinib has been approved as a second-line treatment for advanced gastric cancer. Several phase III studies of liver cancer, non small cell lung cancer and other tumors also showed apatinib has less toxicities and better tolerance. However, the clinical application of apatinib in nasopharyngeal carcinoma is still lack of evidence-based medicine. And this trial is designed to investigate the efficacy and safety of apatinib as maintenance therapy after chemoradiotherapy in nasopharyngeal carcinoma with metastasis.