Tumor growth depends on the tumor microenvironment(TME).Tumor-associated neutrophils(TANs)are important inflammatory cells in TME.TANs are divided intoN1type with anti-tumor effect andN2type of tumor-promoting effect.Therefore,TANs have both beneficial and harmful aspects of the body.A large number of studies have been shown that TANs affect tumor formation,metastasis,angiogenesis and immune response,regulated by the secretion of cytokines and chemokines.This review will summarize the biological characteristics of TANs,and tumor development,prognosis and treatment of tumor as well as research progress of the relationship between TANs and tumor.