Abstract: As we all know, monocytes can enter into the tumor tissues through the blood vessel wall at the various stages of tumor development. These monocytes can differentiate into macrophages, i.e. the tumor-associated macrophages(TAMs), with unique phenotypes. TAMs are important parts of the tumor microenviroment, involved in tumorigenesis, growth, invasion and metastasis, moreover, TAMs transferring into the tumor tissues is a critical step in the development of malignant tumors. In this review, the latest advances of TAMs on tumor microenvironment have been discussed noticeably, cell and animal studies proved that TAMs could make a favorable microenvironment to promote tumor development and progression. Meanwhile, clinicopathological studies suggest that the accumulation of TAMs in tumors is correlated with poor clinical outcome. At last, we also discuss the possibility of using TAM-targeting therapy as a promising novel strategy for cancer therapy.