Abstract: Objective DNA methylation is an important epigenetic regulatory mechanism, which is catalyzed with DNMTs and closely related to tumorigenesis. Currently, it has been found that more than 50 key genes were hypermethylation during the process and development of melanoma. Our study is to investigate the effects of DNA methylase inhibitor 5-AZA on proliferation and migration of human uveal melanoma cells and explore its molecular mechanism. Methods OCM-1 and OCM-3 cells were treated with 4 μM 5-AZA as experimental group, and the cells were treated with DMSO as control group. Then, the effect of 5-AZA on cell proliferation was detected by MTS and cell clone formation assay; the cell cycle was analyzed by flow cytometry; and the effect of 5-AZA on cell migration was evaluated by cell scratch assay; Real-time PCR and Western blotting were used to determine the gene expression of 5-AZA on cell cycle. All data were analyzed using two-tailed t-test to determine statistical significance to assess the difference between the control group and experimental group. Results 5-AZA significantly inhibited the proliferation of human uveal melanoma cells (P<0.01) and the ability of cell clone formation. 5-AZA could induce G₁ phase arrest of human uveal melanoma cells. 5-AZA had no significant effect on the migration of human uveal melanoma cells. 5-AZA significantly could upregulate p21 expression and downregulated CDK2 expression in uveal melanoma cells. Conclusion 5-AZA inhibits proliferation of human uveal melanoma cells by up regulating p21 and down regulating CDK2. And 5-AZA can be applied potentially into clinical treatment of uveal melanoma.