Abstract: Intestinal microbiota are able to influence tumor initiation, progression, as well as therapy through local or systemic inflammation. Currently, the role of intestinal microbiota in cancer treatment is becoming increasingly significant, and investigators have found that intestinal microbiota affect the responsiveness of solid tumor to immune checkpoint inhibitor treatment, but the mechanisms responsible for inter-individual differences in immune responses are unclear. Some scholars believe that gut microbiota may play a potential regulatory role in it, such as Akkermansia muciniphila, lactobacillus and bifidobacterium can regulate the function of tumor cells and immune cells, and promote the production of a variety of cytokines, thereby improving the therapeutic effect of immune checkpoint inhibitors. Therefore, in this paper, the effects of gut microbiota on tumor cells and immune cells, as well as the current status of research on gut microbiota and immune checkpoint inhibitors are described.