Objective：To observe the clinical effect of Dakundan combined with estradiol valerate tablets for infertility due to thin endometrium(EM).Methods：Divided 72 cases of patients with infertility due to thin EM into the observation group and the control group randomly according to the random number table，36 cases in each group.One case of patient in the control group was not excluded according to the treatment plan.Both groups were given oral administration of estradiol valerate tablets，and the observation group was additionally given Dakundan.The treatment for both groups lasted for 3 menstrual cycles.Observed the changes of Chinese medicine syndrome scores，EM thickness，peak systolic blood flow velocity(PSV)of EM helicine artery and resistance index(RI)before and after treatment，and compared the clinical effect and pregnancy rate in the two groups.Results：Compared with that before treatment，the Chinese medicine syndrome scores of the two groups were decreased after treatment(P＜0.05)；the decrease of Chinese medicine syndrome scores in the observation group was significantly lower than that in the control group(P＜0.05).Compared with that before treatment，the EM thickness in the two groups was increased after treatment(P＜0.05)；the EM thickness in the observation group was thicker than that in the control group(P＜0.05).Compared with that before treatment，the PSV of the EM spiral artery in the observation group was increased and RI was decreased after treatment，differences being significant(P＜0.05).There were no significant changes being found in comparisons of PSV and RI of the EM spiral arteries in the control group before and after treatment(P＞0.05).The total effective rate was 88.9%in the observation group and 68.6%in the control group，compared the two groups，difference being significant(P＜0.05).The pregnancy rate was 33.3%in the observation group and 11.4%in the control group，compared the two groups，difference being significant(P＜0.05).Conclusion：The application of Dakundan combined with estradiol valerate tablets has significant curative effect in treating infertility due to thin EM.It can effectively improve EM morphology and local blood flow and promote pregnancy rate.