Objective The aim of this study is to learn the iodine nutritional status of pregnant women in Changping District after the reform of salt industry system,and to provide scientific basis for the adjustment of the prevention and treatment strategies of iodine deficiency disorders in pregnant women. Methods Monitoring is carried out in accordance with Beijing Iodine deficiency Disease Monitoring Program.Changping District of Beijing was divided into five sampling areas according to the east,west,south,north and middle.One street (town) was randomly selected in each area every year,and 20 pregnant women living in this area for more than half a year were randomly selected in each street (town).One random urine sample and household salt were collected to detect the content of urine iodine and salt iodine.To analyze the coverage rate of iodized salt,qualified iodized salt consumption and the urinary iodine level of pregnant women in different years,regions,pregnancy periods and age groups. Results A total of 500 edible salt samples of pregnant women were monitored from 2017 to 2021.The medians of salt iodine in each year were 19.2 mg/kg,22.8 mg/kg,26.7 mg/kg,26.2 mg/kg and 24.2 mg/kg,respectively.The medians of salt iodine increased with years overall (R_s=0.476,P＜0.001).The differences in iodized salt coverage,qualified iodized salt consumption rate and medians of salt iodine among pregnant women in different years were statistically significant (χ² =20.959,P＜0.001;28.533,P＜0.001;225.700,P＜0.001).A total of 500 urine iodine samples of pregnant women were monitored from 2017 to 2021,the medians of each year were 122.0 μg/L,137.4 μg/L,137.5 μg/L,211.8 μg/L,and 192.5 μg/L,respectively.The total median of urine iodine in pregnant women was 148.3 μg/L,and increased with years overall (Rs=0.216,P＜0.001).The proportion of urine iodine content less than 150 μg/L was 50.6 %. Conclusion The iodine nutrition level of pregnant women in Changping District has improved after the reform of the salt industry system,but insufficient iodine nutrition is still one of the main health risk factor for pregnant women in Changping District.