Abstract: Objective To investigate the island adults'iodine nutritional status and the affective factors of urinary iodine concentration and to evaluate the advantages and disadvantages of iodized salt prophylaxis.Methods A contrast study was carried out in 8 countries which were selected from Dinghai(iodized salt district)and Daishan(non-iodized salt district)of Zhoushan island by random sampling.Chi-squared test of contingency table and Kruslal-Wallis test were used to compare the qualitative data and quantitative data respectively.Ordinal regression was used to analyse the affective factors of urinary iodine concentration.Results In iodized salt district,the percent of urinary iodine concentration above 200μg/L was 47.1%,and in non-iodized salt district,the percent of urinary iodine concentration below 100μg/L was 57.2%.In non-iodized salt district,sex,average annual income and daily dietary intake was significant in the final regression model,the value of OR is 0.685,1.224 and 1.201 respectively.Conclusion In Zhoushan island,the daily iodine intake can't match the suggested 150μg/day,the measure of iodized salt prophylaxis is necessary,but the specificity of island diet should be considered,the concentration of iodine in salt should be decreased in order for the urinary iodine concentration within the ideal range.In non- iodized salt district,diary iodine intake could be an assist measure to improve the iodine nutritional status.