Liver cancer was the third cause of global cancer death, while China has the largest number of patients. And traditional Chinese medicine is an important strategy for liver cancer. There into, Huaier polysaccharides (HP), the major component of Trametes robiniophila Murr., as a preparation of Huaier granule, is recommended by clinical guidelines for Hepatocellular carcinoma (HCC). However, the anti-HCC mechanism remains unclear. Herein, we investigated whether HP could suppress HCC and revealed the underlying mechanism. Firstly, HP showed a weaker proliferation inhibitory effect on the mouse source and human HCC cells in vitro, but exhibited stronger anti-HCC effects in animals. And nude mice models confirmed that macrophages play an important role in the anti-HCC effect of HP. Then, we observed that HP reduced the polarization of M2 macrophages in tumor microenvironment and increased the secretion of pro-inflammatory factors by macrophages. Moreover, 16 s rRNA gene sequencing and non-targeted metabolomics analysis revealed that HP altered the gut microbiota and related metabolites. Eventually, antibiotic intervention eliminated the efficacy and reduced the expression of pro-inflammatory factors, confirming that the gut microbiota is a key molecule for HP efficacy. In addition, MTT and EdU assay indicated that Chenodeoxycholic acid (CDCA) were potential microbial metabolites influencing efficacy of HP. In conclusion, our data revealed that Huaier polysaccharides inhibited HCC via gut microbiota mediated M2 macrophage polarization, providing sufficient scientific support for Huaier polysaccharides clinical application and indicating the indispensable role of polysaccharides in life health.