Abstract:【Abstract】 Ovarian cancer is among the most common gynecologic tumors, and its morbidity and mortality were among the highest in gynecologic tumors. Ovarian cancer is mostly diagnosed very late or in advanced stages, because its early symptoms are atypical. The patient will get better treatment if there are some blood indexs can predict ovarian cancer before surgery. Nowadays, some studies have reported that the preoperative regulatory T cells percentage in ovarian cancer were higher than benign ovarian tumor and healthy control, and its correlated with the prognosis and clinicopathological staging of ovarian cancer. In this paper, the relationship between preoperative regulatory T cells level and ovarian cancer will be reviewed.