Objective To explore the clinical effect of Mifepristone combined with Levonorgestrel intrauterine birth control system in the treatment of adenomyosis.Methods A total of 90 patients with adenomyosis who visited the department of gynaecology in Nantong Tongzhou People′s Hospital from January 2018 to January 2020 were selected as the research subjects.According to random number table method,they were divided into control group and observation group,with 45 cases in each group.The control group was treated with Mifepristone,and the observation group was treated with Mifepristone combined with Levonorgestrel intrauterine birth control system.Menstrual volume,uterine condition,levels of follicle generating hormone(FSH),estradiol(E2)and luteinizing hormone(LH)in two groups before and after treatment were compared.Visual analogue scale(VAS)was used to evaluate dysmenorrhea.The incidence of adverse reactions in two groups during treatment was compared.Results Before treatment,there was no significant difference in menstrual volume and VAS score between two groups(P>0.05).After treatment,the menstrual volume of the observation group was less than that of the control group,and the VAS score of the observation group was lower than that of the control group,the differences were statistically significant(P<0.05).Before treatment,there were no significant differences in uterine volume and endometrial thickness between two groups(P>0.05).After treatment,endometrial thickness and uterine volume in the observation group were lower than those in the control group,the differences were statistically significant(P<0.05).Before and after treatment,there were no significant differences in FSH,E2 and LH between two groups(P>0.05).There was no statistical significance in the total incidence of adverse reactions between two groups(P>0.05).Conclusion Mifepristone combined with Levonorgestrel intrauterine birth control system can relieve the degree of dysmenorrhea and reduce menstrual volume in patients with adenomyosis and meanwhile will not cause hormone level fluctuations and increase the incidence of adverse reactions.The effect is remarkable and it is worthy of promotion.