Abstract: Objective To analyze the distribution of iodine nutrition level of key population in Kunshan City during the "13th Five-Year Plan"（2016-2020），provide scientific basis for the formulation of the prevention and control policies of iodine deficiency disease. Methods By the stratified random sampling，the children aged 8-10 years old were selected according to geographical location every year，and their urine samples and edible salt samples were collected to determine the content of urine iodine and salt iodine. Results A total of 1 609 salt samples were collected in Kunshan City from 2016 to 2020. The coverage rate of iodized salt was 97.39%，the qualified rate of iodized salt was 99.49%，and the consumption rate of qualified iodized salt was 96.89%. A total of 1 084 urine samples were collected from children aged 8-10 years old，and the median urine iodine was 202 μg/L. There was statistically significant difference among different years（χ²=26.857，P<0.01）. A total of 525 urine samples of pregnant women were collected，and the median of urine iodine was 154 μg/L. The samples of urine iodine value <150 μg/L accounted for 47.81%. There was no statistically significant difference in the median urine iodine of pregnant women among different years（χ²=4.738，P>0.05）. Conclusion During the "13th Five-Year Plan"，the overall iodine nutrition level of key population in Kunshan City is at an appropriate level，but 24.72% children have excess iodine nutrition and 47.81% of pregnant women have iodine nutrition deficiency，which requires classification guidance for these two groups of people，including strengthen iodine supplements for pregnant women and reducing iodine intake for children.

Key words: Key population, Iodine nutrition, Salt iodine, Urine iodine, Surveillance