Abstract: Objective To observe the clinical efficacy of gonadotropin-releasing hormone agonist (Gn RH-a) in patients with moderate or severe endometriosis after laparoscopic surgery. Methods From January2015 to December 2016, 100 patients who were diagnosed with moderate (stage III) or severe (stage IV) endometriosis were enrolled in a randomized clinical trial in Kunming Maternal and Child Health Hospital. After receiving conservative laparoscopic surgery, patients were randomly divided into a treatment group and a control group. The patients in the treatment group were injected 3.75 mg Gn RH-a (commodity name: Dafilin) for 6 times as a complete treatment. The control group did not receive any drugs after surgery. The two groups were followed up for one year to observe the difference of carbohydrate antigen 125 (CA125) value, VAS scores of pelvic pain, recurrence rate and pregnancy rates between the two groups.Re s ults (1) There was no significant difference between the two groups in CA125 value before and after operation (P>0.05) . (2) No significant difference was observed in VAS scores between two groups before and after surgery (P>0.05) . (3) The treatment group had 4 cases of recurrence (recurrence rate of 4%) , and the control group had 8 cases (8% of recurrence rate) . The comparison of recurrence rate between groups was significantly different (P<0.05) . (4) The pregnancy rate was30% in the treatment group while that was 14 % in the control group. The observed difference in pregnancy rates was statistically significant (P<0.05) . Besides, in the treatment group, 9 patients with stage III endometriosis and 6 patients with stage IV were pregnant while in the control group, the number ofpregnant patients were 6 and 1 in patients with stage III and IV endometriosis.The difference in number of pregnant patients with different stages was statistically significant between two groups (P<0.05) .The in-group comparison showed that there was a significant difference in the number of pregnancies in patient with stage IV endometriosis between the treatment group and the control group (P<0.05) . Age stratified analysis revealed that the pregnant rate among patients aged over 35 was significantly higher in the treatment group than that in the control group (with P <0.05) .Conclus ion Laparoscopic Gn RH-a can reduce the recurrence rate of moderate and severe endometriosis and increase the rate of spontaneous pregnancy in patients over 35 years of age and patients with moderate or severe endometriosis.