Abstract: Gastric cancer (GC) is one of the most resistant malignancy to several treatment strategies.In recent years, the morbidity and mortality of GC has stayed high.Surgical resection remains the main treatment option for GC at present.Although chemotherapy, radiotherapy, immunotherapy, and traditional Chinese medicine are used as adjuvant therapies after surgery, the prognosis and fiveyear survival rate are still low.Currently, there is no effective method for early diagnosis of GC and thus most patients are diagnosed only when the advanced symptoms appear.Exosomes contain and transfer DNA, RNA, proteins, lipids, and other biological macromolecules.Several studies have found that exosomes are involved in tumor processes including cell proliferation and metastasis.In particular, the abundant biological macromolecules present in the exosomes reflect the progress of tumor development thereby enabling them as non-invasive diagnostic markers.This provides a new idea for diagnosing GC in early stages.In this review, the contribution of exosomes to GC metastasis and the applications of exosomes in early GC diagnosis are briefly summarized.