Abstract:Gastric cancer is a malignant tumor that seriously endangers human health. Claudin18.2 (CLDN18.2) is a transmembrane protein and a main component of tight junctions that plays an important role in maintaining barrier function. Under normal physiological conditions, CLDN18.2 is not expressed in healthy tissues, but it is expressed in differentiated epithelial cells of the gastric mucosa. With the progress of research, it has been found that CLDN18.2 is highly expressed or ectopically activated in primary malignant tumors such as gastric cancer, esophageal cancer, ovarian cancer, pancreatic cancer, lung cancer, and breast cancer. Due to its potential for specific expression, CLDN18.2 has become a new emerging target in anti- tumor drug development. This article reviews the expression characteristics, regulation and clinical pathological features, of CLDN18.2 in gastric cancer, and the progress of clinical drug research targeting CLDN18.2.