Objective:To study the effect of vitamin D on rat lung morphogenesis. Methods:Sprague-Dawley pregnant rats were divided into 3 groups randomly including normal control group, vitamin D deficiency experiment model group and intervention group, with 6 rats in each group. We fed the model and intervention groups with fodder without vitamin D away from light, while the control group received normal fodder and normal light for two weeks. Then the female rats in two groups copulated with normal male rats. On days E17d, E18d and E19d, each rat of the intervention group received intragastric administration with active vitamin D (0.5 mg/kg), and they regained light and normal fodder. The morphology of fetal rat lungs on E20d and the 1-day-old neonatal rat lungs were observed by light microscope and electronic microscope. Results:Under the light microscope, smaller alveolar space, smaller respiratory membrane’s diameter and thicker alveolus mesenchyma were shown in lungs of vitamin deficient model group compared with control group(P < 0.05). Significant difference was found between the model and intervention group in neonatal lung (P < 0.05) but not in E20d fetal lung(P > 0.05). With the electronic microscope, fewer lamellar bodies but more glycogen deposition in intracytoplasm were detected in the fetal lung of E20d in experimental model group than controls. While in the model group of 1d after birth, despite of the number, the lamellar bodies were not as condensed as control, empty lamellar bodies were found. However, such changes were less sever after the supplement of active vitamin D. Conclution:Vitamin D deficiency in generation could inhibit the development of rat lung morphogenesis. Supplement with active vitamin D may reverse the inhibition.