Abstract: Gynecological malignancies are detrimental to women's health, among which ovarian cancer has the highest mortality rate. It is characteristic of high morbidity rate, insidious process, early diagnosis difficulty and poor prognosis. Though great breakthrough has been made in the study of the cellular and molecular biology of ovarian cancer, the survival rate of this malignancy has not changed greatly since platinum-based-treatment was introduced to treat ovarian cancer more than thirty years ago. One reason for this high mortality rate is the lack of effective tools for detection in early stage of ovarian cancer. Hence, a high specific and sensitive biomarker is necessary. Recent studies mainly focus on MicroRNA (miRNA). miRNA is a class of endogenous non-coding RNA molecule, which plays an important role in gene expression by degradation or translation inhibition through base-pairing to complementary sites on the target mRNAs, usually in the 3'untranslated region. miRNA participates in almost all biological processes, including cell cycle regulation, cell proliferation, inflammation and tumorigenesis. Multiple studies show that plasma miRNA expression profiles can distinguish different types, stages and differentiation of ovarian cancer. For example, compared with healthy individuals, patients with endometriosis associated ovarian cancer, patients with endometriosis and patients with epithelial ovarian cancer have different plasma miRNA expression profiles. What's more, miRNA can regulate the tumorigenesis, progression, metastasis, drug resistance and recurrent of ovarian cancer, which closely correlate with survival rate of patients and offers abundant information for the treatment as well as prognostic evaluation. In conclusion, miRNA plays a key role in ovarian cancer, and it is an excellent biomarker for early diagnosis and prognosis evaluation of ovarian cancer.