Abstract ： Objective ： To observe the clinical effect of levonorgestrel intrauterine system combined with modified Shaofu Zhuyu tang for patients with dysmenorrhea due to adenomyosis and its mechanism. Methods：A total of 120 cases of patients with dysmenorrhea due to adenomyosis were included and divided into the western medicine group and the combination group according to the random number table method，60 cases in each group. The western medicine group was treated with levonorgestrel intrauterine system， and the combination group was additionally treated with modified Shaofu Zhuyu tang. The clinical effect， the Chinese medicine syndrome scores， the scores of dysmenorrhea， the indexes of serology and treatment safety in the two groups were analyzed. Results： The total effective rate was 93.3% (56/60) in the combination group， significantly higher than that of 75.0% (45/60) in the western medicine group， the difference being significant(P＜0.05). After treatment，the Chinese medicine syndrome scores，the scores of dysmenorrhea and the indexes of serology in the two groups were decreased when compared with those before treatment(P＜0.05)；the Chinese medicine syndrome score，the score of dysmenorrhea and the levels of carbohydrate antigen(CA)125，tumor necrosis factor- α and interleukin- 8 in the combination group were significantly lower than those in the western medicine group(P＜0.05). The incidence of adverse reactions was 1.7%(1/60) in the combination group，and 3.3 %(2/60) in the western medicine group， there being no significance in the difference(χ 2=0.342， P=0.559). Conclusion： For patients with dysmenorrhea due to adenomyosis，the therapy of levonorgestrel- releasing intrauterine system combined with modified Shaofu Zhuyu tang can effectively relieve symptoms，inflammation and infiltrative growth of endometrium，with high safety.