Objective To summarize the value of serum thyroglobulin (Tg) in diagnosis before surgery and monitoring after surgery for differentiated thyroid cancer (DTC). Methods By using the method of literature review, the literatures related to the diagnosis and monitoring value of serum Tg for DTC were studied. Results ① Serum thyroglobulin had a certain value in diagnosis of thyroid nodules, especially in follicular cancer or Hürthle cancer whose diagnosis undetermined by fine-needle aspiration biopsy (FNAB), and it was closely linked with the tumor’s size and distant metastasis of the DTC. ② Raise of serum Tg postoperatively was important for judging the recurrence and metastasis of DTC. However, how to establish an appropriate threshold of serum Tg, identify the differences of results for different measurement methods, make the accurate judgment for false positive and false negative, and combine with other imaging methods appropriately, needed our attention. Conclusion Serum Tg plays a very important role in diagnosis before surgery and monitoring after surgery of DTC, clinical doctors need pay high attention on it.