Abstract: Due to the abundance of bioinformatic molecules in exosomes, they provide potential biomarkers and have shown good clinical application prospects in in vitro diagnostics of tumors. This paper provides a detailed introduction to the functions of extracellular vesicles, elaborates on their advantages in in vitro diagnostics, gives an overview of the detection methods of extracellular vesicles, and delves into the value and clinical approvals of extracellular vesicles in the diagnosis of lung cancer, colorectal cancer, ovarian cancer, gastric cancer, pancreatic cancer, bladder cancer, bone and soft tissue sarcoma, etc., with a prospect of the development trend of extracellular vesicles in the field of in vitro diagnostics.