Hepatocellular carcinoma (HCC) is one of the most common and fatal cancers in the world. Tumor metastasis is an important factor of poor prognosis in patients with HCC. Tumor hypoxia can promote tumor cell metastasis in HCC. Epigenetic modification is closely related to tumor hypoxia and metastasis. In our previous research, we found that basil polysaccharide suppressed migration and invasion of HCC cell by inhibiting hypoxia induced histone methylation in vitro. In the present study, we investigated the effect of basil polysaccharide on the walker 256 carcinoma cell metastasis in rat. We established an intratumoral hypoxic model in rat by hepatic artery ligation (HAL). Then rats were treated with basil polysaccharide (75, 150 and 300mg/kg). The results showed that HAL could promote tumor metastasis by aggravating tumor hypoxia. However, basil polysaccharide could inhibit tumor metastasis in intratumoral hypoxia. Further, we demonstrated that basil polysaccharide could down-regulate the expression of HIF-1α, G9a, LSD1, JMJD1A, JMJD2B, JARID1B and H3K9me2. Synchronously, basil polysaccharide could increase E-cadherin and VMP1 expression, and decrease N-cadherin, vimentin and β-catenin expression. The results indicated that histone modifying enzymes might be a new therapeutic target of basil polysaccharide on hepatocellular carcinoma metastasis.