The common tumor marker for cholangiocarcinoma is CA199, which remains elevated after surgery on the one hand, because it has not been fully metabolized after surgery, or because it recurs again after surgery. CA199 is a special substance secreted and produced by cholangiocarcinoma cells, and the level of CA199 will be obviously elevated before treatment. There are two main reasons why CA199 level is still high in postoperative patients. On the one hand, it is due to the fact that patients’ postoperative time is still short, and the accumulated CA199 in the body is not completely metabolized. On the other hand, the CA199 level will rise again when the tumor recurs for a longer period of time after surgery. If CA199 rises again after surgery, patients with cholangiocarcinoma need to have outpatient review in time.