Abstract: Objective: To explore the effects of EZH 2 gene on proliferation and metastasis of human ovarian cancer cell, and the mRNA and protein expression of EZH2 in ovarian carcinoma tissue, as well as its clinicopathologic signifi-cance. Methods:Small interfering RNA (siRNA) targeting EZH 2 was applied to transiently knock down EZH2 in ovarian can -cer OVCAR- 3 cells, and then the protein expression of EZH2 in the OVCAR- 3 cells was analyzed by Western blotting. The level of cell proliferation was determined using MTT assay, and the invasive and migrative ability were examined by Tran -swell assay. RT-PCR and immunohistochemistry was used to detect the EZH 2 mRNA and protein status in ovarian cancer tissue, respectively. Results: Compared with the negative controls, EZH 2 siRNA could effectively reduce the protein expres -sion levels of EZH2 in OVCAR- 3 cells and could significantly inhibit the proliferation of the cells (P= 0.032 ). The number of invaded and migrated OVCAR-3 cells was significantly less in siEZH2 group than in siLuc group, respectively invasion: (29.3 ± 5) vs (51± 6.8), P=0.027 ; migration: ( 51.6 ± 7.7) vs (72.3 ± 11.7), (P=0.036 ). The upregulated EZH 2 mRNA expression was examined in ovarian cancer tissues compared with normal ovary. The immunohistochemistry for EZH 2 high expression was detected in 61% of ovarian cancer tissues and its expression was positively correlated with T stage, lymph node metas-tasis and FIGO stage. In univariate analysis, a significant relationship between high expression of EZH 2 and shortened pa -tient survival (P=0.007 ) was displayed. Multivariate analysis indicated EZH2 expression (P=0.047 ) was evaluated as an in-dependent prognostic parameter. Conclusion : EZH2 plays an important role in the tumorigenesis and progression of ovari-an carcinoma. High expression of EZH2 is an independent molecular marker of unfavourable prognosis in the patients with ovarian carcinoma.