The aim of the present study was to investigate the association between KDM3A expression and the clinicopathological parameters of patients with epithelial ovarian cancer (EOC). KDM3A expression was analyzed using immunohistochemistry in EOC tissue microarray containing 90 paired cases of EOC and matched normal control. The expression level of KDM3A protein in EOC tissues was significantly higher than that of adjacent normal control tissues. In addition, positive expression of KDM3A correlated with the metastases. Furthermore, Kaplan–Meier survival analysis showed that a high expression level of KDM3A resulted in a significantly poor prognosis of EOC patients. Knock-down of KDM3A could suppress both the proliferation, migration and invasion in vitro EOC cell lines OV-2008 and ES-2. Additionally, knock-down of KDM3A not only could enhance cellular apoptosis induced by Cisplatin and Paclitaxel, but also induced some pro-apoptotic genes expression. Our data is the first to demonstrate that increased KDM3A expression in EOC is significantly associated with metastases and poor prognosis; and that KDM3A promotes the proliferation, migration and invasion of EOC cells. Knock-down of KDM3A may be an important complement to EOC that is resistant or refractory to chemotherapy.