We reported the first case of thin endometrium patient with twin conceived via transdermal therapy during frozen-thawed embryo transfer (FET). The patient used Progynova administration to preparate endometrium in the first FET cycle. The endometrial thickness was 5.0 mm after 10 days of Progynova administration, the cycle was cancelled. In the second FET cycle, the transdermal therapy was used to support the endometrial development. The endometrial thickness reached 7.6 mm, two embryos were transferred on the day 4 of progesterone intramuscularly. The patient was carrying twins for nine months. There is a speculation that transdermal therapy may be effective for patients with thin endometrium during FET and provide a new method of clinical treatment.