Exosomes are nanometer-sized vesicles produced by the fusion of multivesicular bodies and cell membranes which are widely distributed in almost all body fluids such as blood，urine，pleural and peritoneal effusions. As an important role of intercellular communication and genetic material carrier，exosomes play its biological function by stimulating target cells directly through the transfer of various bioactive molecules such as cell membrane receptors，proteins，messenger RNAs（mRNAs）and micro RNAs（miRNAs）. Tumor-derived exosome（TEX）is a type of exosome secreted by tumor cells which not only has the general characteristics of exosomes but also has special features. Studying the effect of TEX will open up a whole new way to diagnosis and treatment of tumor.