摘要Intestinal flora affects the maturation of the host immune system,serves as a biomarker and efficacy predictor in the immunotherapy of several cancers,and has an important role in the development of colorectal cancer(CRC).Anti-PD-1/PD-L1 antibodies have shown satisfactory results in MSI-H/dMMR CRC but performed poorly in patients with MSS/pMMR CRC.In recent years an increasing number of studies have shown that intestinal flora has an important impact on anti-PD-1/PD-L1 antibody efficacy in CRC patients.Preclinical and clinical evidence have suggested that anti-PD-1/PD-L1 antibody efficacy can be improved by altering the composition of the intestinal flora in CRC.Herein,we summarize the studies related to the influence of intestinal flora on anti-PD-1/PD-L1 antibody efficacy in CRC and discuss the potential underlying mechanism(s).We have focused on the impact of the intestinal flora on the efficacy and safety of anti-PD-1/PD-L1 antibodies in CRC and how to better utilize the intestinal flora as an adjuvant to improve the efficacy of anti-PD-1/PD-L1 antibodies.In addition,we have provided a basis for the potential of the intestinal flora as a new treatment modality and indicator for determining patient prognosis.