Background: Enhancer of zeste homolog-2 (EZII2), a histone methyltransferase that regulates histone H3 methylation of lysine27 (H3K27me3), is involved in the pathogenesis of myelodysplastic syndrome (MDS). Targeting epigenetic regulators has been identified as a potential treatment target in MDS chemotherapy. Curcumin, a natural compound extracted from turmeric, was found to possess a wide range of anticancer activities in various tumors. Methods: This study was designed to investigate the inhibitory effect and action mechanism of curcumin in myelodysplastic syndrome (MDS) in vitro and in vivo. Results: Our results showed that curcumin can significantly suppress cell proliferation and induce cell apoptosis and cell cycle arrest in human MDS-derived cell lines. It reduced EZH2, DNA methyltransferase 3A (DNMT3a), ASXL1 and downstream H3K4me3, H3K27me3 and HOXA9 expression and inhibited EZH2 and H3K27me3 nuclear translocation. Curcumin also showed anti-cancer effects in a xenograft mouse model and reduced EZH2, H3K4me3 and H3K27me3 in vivo. EZH2 knockdown can reduce the H3K27me3 levels and induce curcumin resistance in vitro but attenuates leukemic transformation in vivo. Conclusion: These findings provide the potential molecular mechanism of curcumin as a therapeutic agent for MDS.