Taken together, by investigating the multiple aspects of thyroid functional status in L-NAME-induced preeclamptic rats, our results demonstrated for the first time that the ultrastructure of thyroid follicular cell and hepatic Dio1 expression could be significantly impaired by preeclampsia, and all the damages were ameliorated after antihypertensive therapy, which provides the reliable evidence for understanding the underlying mechanism of hypothyroidism in preeclamptic condition. Here, DIO1 is linked to hypothyroidism.