Investigations have confirmed that coastal areas in China are mildly iodine deficient, and therefore, salt iodization interventions have also been implemented. Some people believe that residents in coastal areas have a greater chance to consume seafood, therefore, they are worried about over-iodizing iodine if they consume iodized salt again, or even believe that there is no need to consume iodized salt. in 2009, China’s health department conducted a survey on the dietary iodine intake of residents in coastal areas in four provinces (cities), including Fujian, Shanghai, Zhejiang and Liaoning. The survey results showed that the frequency and amount of iodine-rich foods such as seaweed and nori were very low among residents, and the proportion of dietary iodine intake from such foods in coastal areas was very low. Without taking into account cooking losses, 84.2% of iodine in the diets of coastal residents comes from iodized salt, while only 13.1% comes from various foods (including 2.1% from seaweed, nori and sea fish) and 2.7% from drinking water. Therefore, there is a need to popularize iodized salt in coastal areas to ensure iodine intake and reduce the risk of iodine deficiency.