Abstract Objective To study the effect of low-dose mifepristone and levonorgestre- releasing intrauterine system (LNG-IUS) in the treatment of adenomyosis, and to evaluate the efficacy of low- dose mifepristone in reducing intermenstrual vaginal bleeding for placement of LNG-IUS. Methods 84 patients with adenomyosis were randomly divided into two groups, 42 cases were in each group, the treatment group treated with low-dose mifepristone combined with LNG-IUS, the control group treated with LNG-IUS, the clinical curative effect and adverse reaction were observed at 3 months, 6 months, 12 months and 24 months after treatment. Results Patients of the two groups at 6 months, there was no significant difference in the total efficiency. After 3 months of treatment, the days of intermenstrual bleeding and menses of patients in the treatment group were more than that of the control group (P<0.05), at the treatment of 3 months and 6 months , the number of patients with irregular vaginal bleeding in the control group was more than that of the treatment group (P<0.05), at the other time of menses in the treatment, there was no statistically significance between two groups (P<0.05). The VAS scores of dysmenorrheal of the patients after treatment gradually decreased than before treatment, the difference was statistically significant (P<0.05), the difference was not statistically significant at different time between groups (P>0.05); Compared the incidence of adverse reactions between the two groups ,there was no significant difference (P>0.05). Conclusion Low- dose of mifepristone combined with LNG-IUS in the treatment of adenomyosis has definite effect, and it can reduce the irregular vaginal bleeding effectively, it can be used as the optimum scheme of adenomyosis.