Ovarian cancer ranks as the fifth common tumour in women and is the leading cause of cancer-related death among the women. Long non-coding RNAs (lncRNAs) play crucial roles in the development of tumors. However, the expression and the role of EWSAT1 in ovarian tumor are still unknown. In our study, we found the expression of EWSAT1 was upregulated in ovarian cancer cell lines and samples. Ecoptic expression of EWSAT1 suppressed miR-330-5p expression in ovarian cancer cell. In addition, the expression of miR-330-5p was downregulated in ovarian cancer cell lines and samples. Moreover, the expression of miR-330-5p was negatively related with the expression of EWSAT1 in ovarian cancer samples. Furthermore, we identified Pdia3 was a direct target gene of miR-330-5p. Ecoptic expression of miR-330-5p suppressed Pdia3 expression and overexpression of EWSAT1 promoted Pdia3 expression in ovarian cancer cell. In addition, Ecoptic expression of miR-330-5p promoted ovarian cancer cell proliferation, colony formation and invasion. Overexpression of EWSAT1 increased ovarian cancer cell proliferation, colony formation and invasion through targeting miR-330-5p. These data suggested that EWSAT1 might act as an oncogene in the development of ovarian cancer partly through inhibiting miR-330-5p expression.