Tumor marker testing is getting more and more attention, but how to understand the value of tumor marker testing? Firstly, we should see whether the test value is very obviously elevated, which is often more than ten times or even higher than the reference range; secondly, the abnormal test result at one time cannot explain the problem, and we must observe whether the item is in a dynamic elevated trend within a certain period of time. If the value of this level may be your own reference range if there are no clinical symptoms), but if the value of several tests will be in the trend of dynamic increase, it should be brought to our attention. Most of them are neither organ-specific nor tumor-specific and can hardly be used for early diagnosis of tumors. They can only provide opportunities for clinical surgical cure. Because of the low sensitivity in the initial and early stage of tumor, they should not be used for asymptomatic early screening of the population. Generally speaking, there is a good correlation between the serum concentration of tumor markers and the stage of tumor development, and its sensitivity is highest in tumor development and lower in early stage, so the current tumor markers are meaningless for early screening of asymptomatic people. For different individuals suffering from the same tumor or tumors of the same organ, the size, developmental stage and prognosis of their tumors cannot be compared by measuring the concentration of tumor markers. Some individuals have advanced tumor development, but the tumor markers are not secreted high or not secreted at all. At present, there is no international standard except for AFP.CEA, and other items can only be measured with relative accuracy.