A thin endometrium can lead to low clinical pregnancy rates, low live birth rates, high spontaneous abortion rates, and low birth weight. However, current methods of treating thin endometria do not achieve ideal results. This study explored the effect of Indian Hedgehog (IHH) on thin endometrium and its mechanism of action. A thin endometrial rat model was established by infusion of 95% ethanol. IHH was overexpressed in model rats using adeno-associated viruses. The endometrial thickness and number of glands and vessels were determined using H&E staining. Endometrial fibrosis was detected using Masson's trichrome staining. Immunohistochemistry was performed to detect α-SMA, MUC-1, and CK19. After modeling, the rats were mated, and the number of gestational sacs was counted for fertility assessment. Western blotting was used to detect the angiogenesis markers vWF, PCNA, and vim and Hedgehog signaling-related proteins SMO, GLI1, and GLI3. IHH overexpression reduced ethanol-induced edema and bruising, repaired the appearance of damaged tissue, increased endometrial thickness, promoted glandular and vascular regeneration, and alleviated endometrial fibrosis. IHH overexpression inhibited the expression of fibroblast marker α-SMA while promoting the expression of vWF, PCNA, vim, CK19, and MUC-1. It also increased the number of gestational sacs and promoted the expression of SMO, GLI1, and GLI3. In conclusion, IHH ameliorates ethanol-induced thin endometrium and improves fertility by activating the Hedgehog signaling pathway.