Objective To evaluate the clinical efficacy and adverse reactions of gonadotropin-releasing hormone agonist(GnRH-a)combined with Levonorgestrel Intrauterine Sustained-release System(LNG-IUS)in the treatment of adenomyosis.Methods A total of 80 patients with adenomyosis admitted to Dezhou Maternal and Child Health Hospital from October 2019 to October 2021 were selected as research objects,and they were divided into control group and observation group according to random number table method,with 40 cases in each group.The control group was treated with LNG-IUS.Observation group was treated with GnRH-a and LNG-IUS.Uterine volume,hemoglobin level,carbohydrate antigen 125(CA125)level,visual analogue scale(VAS)score and adverse reactions were compared between the two groups.Results The uterine volume of the observation group after treatment was smaller than that of the control group,and the hemoglobin level,VAS score and CA125 level were lower than that of the control group,with statistical significances(P＜0.05).There were no significant differences in the incidence of weight gain,mood depression,sleep disorders and IUD downshift/detachment between two groups (P＞0.05).The incidence of hot flashes,sweating and vaginal dryness in the observation group was higher than that in the control group,and the incidence of irregular vaginal bleeding was lower than that in the control group,the differences were statistically significant (P＜0.05).There was no significant difference in the total incidence of adverse reactions between two groups (P＞0.05).Conclusion GnRH-a combined with LNG-IUS has a good therapeutic effect on adenomyosis and has high clinical application value.The adverse reactions of the combined use of GnRh-A and LNG-IUS are mainly related to menopause symptoms.