Abstract: It has become increasingly apparent that cancer progression and outcome is not solely dependent on the characteristics of the tumor but on the tumor microenvironment as well.Tumor-associated macrophages(TAMs), which constitute a significant part of the tumor-infiltrating immune cells, are "educated" towards an anti-tumor M1 phenotype or pro-tumor M2 phenotype by different signals of the tumour microenvironment.Whereas the vast majority of studies with numerous tumor types show that the presence of TAMs in the tumor microenvironment is associated with a worse prognosis, which suggests polarization of TAMs towards the M2 phenotypes, most studies in colorectal cancer claim the opposite, suggesting the polarization of TAMs towards the M1 phenotype, Meanwhile, some in vivo and in vitro experiments have found that TAMs promote the proliferation and metastasis of colorectal cancer.Some other studies have found that tumor microenvironment can induce the functional polarization of macrophages toward a mixed M1/M2 phenotype, and that the function of TAMs could be changed with their location and stage of tumor.In this review, we summarize the different and controversial effects that TAMs play in colorectal cancer.