Tumor markers are a class of substances synthesized or released by tumor cells or produced by the body in response to tumor cells. The main tumor markers found today are: methemoglobin, carcinoembryonic antigen, glycogen 125, glycogen 153, glycogen 19-9, glycogen 724, glycogen 211 and so on. Most of the tumor markers known today exist not only in malignant tumors, but also in benign tumors, embryonic tissues, and even normal tissues. In our normal work, we found that high tumor markers do not necessarily have cancer, and patients who have been clearly diagnosed with cancer do not have high tumor markers. Therefore, the specificity and sensitivity of certain tumor markers are poor, which means that the false positive and false negative rates are high and have only limited reference value. If there is only a single mild elevation or no major change in the results of each test, it does not indicate the development of cancer. If it is progressively elevated, it should be taken seriously, especially if it is high before surgery, low after surgery, and then high again after a period of time, it should be highly regarded as a possible sign of tumor recurrence. If a certain tumor marker or several tumor markers are found to be persistently elevated in physical examination, then vigilance should be raised and further examination by CT, ultrasound, endoscopy and other methods should be conducted. Especially, pathology is the gold standard for tumor diagnosis.