Objective To compare the clinical efficacy between staged acupuncture based on "thoroughfare vessel is the sea of blood" theory combined with routine hormone replacement cycle treatment and routine hormone replacement cycle treatment for patients with recurrent implantation failure（RIF） of thin endometrium. Methods A total of 72 RIF patients with thin endometrium were randomly divided into an observation group and a control group

36 cases in each group. The patients in the control group were treated with routine hormone replacement cycle treatment. Based on the treatment of the control group

the patients in the observation group were treated with staged acupuncture based on "thoroughfare vessel is the sea of blood" theory. The main acupoints were Neiguan（PC 6） and Gongsun（SP 4）

and the supplementary acupoints were selected according to the menstrual cycle and syndrome differentiation; the acupuncture was given once every other day

3 times a week

for 3 consecutive menstrual cycles. The thickness and shape of endometrium

and Hamilton anxiety scale（HAMA） score were observed at implantation window before and after treatment; the clinical pregnancy rate

live birth rate and cycle cancellation rate were compared between the two groups; the correlation between endometrial thickness and HAMA score was analyzed. Results Compared before treatment

the endometrial thickness in the two groups and the proportion of type A+B endometrium in the observation group were increased（P<0.05）

and the HAMA scores in the two groups were decreased（P<0.05） after treatment. The above indexes in the observation group were superior to those in the control group（P<0.05）. The clinical pregnancy rate and live birth rate in the observation group were higher than those in the control group（P<0.05）

and the cycle cancellation rate was lower than that in the control group（P<0.05）. There was a negative correlation between endometrial thickness and HAMA score（P<0.05）. Conclusion Based on the routine hormone replacement cycle treatment

the addition use of staged acupuncture based on "thoroughfare vessel is the sea of blood" theory could improve the thickness and shape of endometrium

relieve anxiety

increase the clinical pregnancy rate and live birth rate

and reduce the cycle cancellation rate in RIF patients with thin endometrium. The curative effect is superior to the routine hormone replacement cycle treatment alone.