Abstract: Polysaccharide is one of the most important pharmacological active substances in seaweed, and has become a new drug resource in tumor treatment. However, the anticancer mechanisms of most microalgal polysaccharides remain to be elucidated. In order to explore the anti-tumor mechanism of Dunaliella salina exopolysaccharide (DsEPS), its toxicity and growth inhibition on cervical cancer cells (Hela) were studied and analyzed, and its anti-tumor activity mechanism was revealed by transcriptome analysis. The results showed that, DsEPS could inhibit Hela cell proliferation, reduce cell viability and change cell morphology. Transcriptome analysis revealed 2032 differentially expressed genes between the control group and the polysaccharide group, 1132 of which were up-regulated and 900 down-regulated. The results of gene function enrichment analysis showed that differentially expressed genes significantly enriched apoptosis and tumor-related biological processes, and participated in a variety of cancer and apoptosis-related signaling pathways, including MAPK signaling pathway, TNF signaling pathway, VEGF pathway, Ras signaling pathway, etc. The top 10 Central genes with the strongest degree of centrality were selected from the PPI network. This study suggests that DsEPS had anti-tumor activity, and preliminarily explores its anti-tumor mechanism, which provides an effective reference for further research in the future.