Abstract: Objective To explore the levels of urine iodine in mothers and urine iodine and blood thyroid-stimulating hormone (TSH) in their neonates, and the correlations. Methods A total of 695 pairs of mothers and their neonates were included. Urine sample of both mothers and newborns were collected and the levels of urine iodine were detected. Heel blood sample of newborns were collected and the levels of TSH were detected. Results The median urine iodine level in 695 mothers was 212.9 μg/L, among whom 163 case (34.39%) were iodine deficient (< 149 μg/L), 143 cases (20.58%) adequate ( ≥ 500 μg/L), 163 case (23.45%) more than adequate (250 ~ 499 μg/L) and 150 case excessive ( ≥ 500 μg/L). The median urine iodine level in neonates was 345.7 μg/L and was positively correlated with mothers’ (rs = 0.576, P < 0.001). The median TSH level in neonates were 3.24±1.75 mIU/L, among whom 88 cases (12.66%) were higher than 5 mIU/L. The TSH level and the proportion of neonates with TSH > 5 mIU/L in neonates whose mother were iodine deficient or excessive were higher than those in neonates whose mother were iodine adequate or more than adequate, and the difference was statistically significant (P < 0.05). Conclusions The investigation found that the level of iodine in mothers was adequate, but there was still a high proportion of iodine deficiency or excess. The levels of urinary iodine in mothers were closely related to those in newborns. There is a high risk for mothers with iodine deficiency or excess to give birth to infants with higher level of TSH.