Objective To explore the application value of CA125 detection in the diagnosis and treatment of ovarian endometriosis cyst,to provide a reference for clinical diagnosis and treatment.Methods 51 patients with ovarian endometriosis cyst were selected as the observation group,and 51 patients with non endometriosis of benign ovarian cyst were selected as control group.The serum CA125 level was detected and compared between the two growps.Results Before operation,the serum CA125 level of the observation group was (95.29 ± 55.47) U/ml,which was significantly higher than that of the control group (17.96 ± 6.82) U/ml (P ＜ 0.05).In the observation group,serum CA125 level of patients with endometriosis clinical pathological stage Ⅱ-Ⅳ was significantly higher than that of patients with stage Ⅰ (P ＜ 0.05).The endometriosis clinical TNM stage was positively correlated with preoperative serum CA125 level in the observation group (r =0.8795,P ＜ 0.05).The preoperative serum CA125 level in patients with dysmenorrhea score 1 point,2 points,3 points was significantly higher than that in patients with dysmenorrhea score 0 point (P ＜ 0.05).The preoperative serum level of CA125 was positively correlated with dysmenorrhea score in the observation group (r =0.5594,P ＜ 0.05).Conclusion The detection of serum carbohydrate antigen CA125 level has important value in diagnosis,treatment and prognosis of ovarian endometriosis.