Abstract: LNG-IUS is an intrauterine contraceptive system also licensed for the treatment of endometriosis. Lots of researches，both at home and abroad ，have shown that LNG-IUS can make the endometrial atrophy，inhibit it's proliferation and prompt its thinning，then reduce the content of upstream into the peritoneal cavity ，and prevent the plant of ectopic endometrium，finaly.At present，there are many researches have reported the molecular mechanism associated with the treatment of LNG-IUS for endometriosis. Most of them focus on apoptosis，related factor of blood vessels formation， and sex hormone receptors.Now we will make a review for this molecular mechanism.

Key words: Endometriosis, Levonorgestrel, Delayed-action preparations, Endometrium