Once esophageal cancer is diagnosed, the extent of cancer invasion should be clarified as soon as possible. The staging of esophageal cancer requires the collection of various examination results to make a comprehensive judgment on the extent of cancer invasion. Staging will help doctors decide what other tests the patient needs to undergo, make judgment on the condition, and then formulate the most suitable treatment plan. Usually, esophageal cancer is staged twice. The first staging is carried out before treatment, which is also known as clinical staging or known as baseline staging; the second staging is completed after surgery, which is known as pathological staging or post-surgical staging. Obviously, the staging is more accurate after surgery because the doctor has more information, especially the analysis of intraoperative conditions and postoperative specimens. The main basis for the doctor to determine the treatment plan is the postoperative pathological staging, and some patients are not able to undergo surgical treatment for various reasons, and the staging can only stay at the level of clinical staging (baseline staging).