Downexpression of miRs was associated with tumor development, progression, and metastasis. This study explored the levels of miR-125b in patients with and to assess its diagnostic value and monitor treatment responses for patients with . A total of 379 individuals were recruited and assigned into the study groups. RT-qPCR analysis was performed to confirm the association of miR-125b levels with tumor stages and treatment responses. The median levels of miR-125b in patients with EOC were significantly lower than that other controls (P < 0.0001). miR-125b in patients with high FIGO stage (III+IV), lymph node metastasis and chemoresistance were lower than that in patients with early-stage (stage I+II; P < 0.001), without lymph metastasis (p= 0.032) and chemosensitivity (P< 0.001). Low levels of miR-125b had a poor prognosis in patiens with . Using a median value of 0.748 to separate EOC from other controls, the sensitivity and specificity reached 0.76 (95% CI 0.75 to 0.85) 0.416 (95% CI 0.26 to 0.55), respectively. miR-125b showed a statistically significant difference between preoperative and postoperative patients in surgical patient groups (P = 0.003). miR-125b levels was lower in patients with chemoresistance that that in patients with chemosensitivity (P< 0.0001). Serum miR-125b in combination with serum CA125 improved both sensitivity and specificity in diagnosis of EOC (P< 0.001). This study demonstrated that miR-125b levels were a useful diagnostic biomarker and biomarker to predict the responses to chemotherapy in patients with EOC.