In the process of solid tumor transformation, the expression of claudins is often dysregulated. Claudins are involved in almost all aspects of tumor biology and steps of tumor development, suggesting that they have the potential to be diagnostics, and prognostic biomarkers and therapeutic targets. Current studies have found that Claudin18.2 is overexpressed in gastric cancer, pancreatic cancer, ovarian cancer and other diseases. Targeted anti-tumor therapy based on Claudin 18.2 has become a research hotspot recently. Therefore, this article reviews the basic structural characteristics of Claudin18.2, its expression in various malignant solid tumors, the progress of research and application, and prospect.