Objective To understand the current situation of iodine supplement for pregnant women,and to explore the effect of kelp on iodine supplement for pregnant women,so as to provide theoretical basis for scientific iodine supplement for pregnant women. Methods A total of 344 pregnant women were selected to investigate the basic situation and iodine supplement. Then pregnant women who did not eat iodine rich food within one week before the survey were selected to eat kelp once without changing the daily household edible salt. The amount of kelp consumed was counted,the iodine content of kelp consumed was detected,the urine iodine of pregnant women in the morning before eating kelp and in the morning after eating kelp was detected,and the change of urine iodine level was observed. Results A total of 344 pregnant women were surveyed. In addition to eating iodized salt,184 pregnant women received iodine supplementation and 160 pregnant women who did not receive iodine supplementation within 1 week before the survey. The complementing strategy was all via eating seafood and the complementing cycle were all random. 104 pregnant women participated in the iodine supplementation intervention study,the average consumption of kelp was (42.39 ± 13.28) g,and the average iodine content of the consumed kelp was (1.09±0.78) mg / g. There were significant difference between the content of iodine urine and the content of iodine after eating kelp on the first,second and third day (P＜0.05). The urine iodine level was the peak on the first day after kelp,then gradually decrease,return to pre-edible level on the 4th day. Conclusion In addition to eating qualified iodized salt,pregnant women with iodine deficiency should eat kelp once a week,which can basically guarantee the iodine nutrition level.