The gastric cancer is the second most malignant tumor that threats human lives due to high incidence and poor prognosis. The prognosis of gastric cancer is closely related to staging, recurrence, and metastasis. The improvement of its prognosis relies on early diagnosis, early treatment, and reasonable postoperative monitoring. Serum tumor markers (TM) are valuable for early diagnosis and postoperative monitoring because their detection is convenient and highly repetitive. This paper introduces features of traditional serum TMs of gastric cancer, including CA125, CA199, CA724, and CEA; presents research progresses of several new TMs, such as PG, MG7, VEGF and HER2; and reviews the practical value and prospects of TM for the diagnosis and treatment of gastric cancer.