Abstract: Objective To study the dose-reaction relationship between different iodine and the morphology and function of thyroid in mice.Methods KM mice after weaning were divided into seven groups by randomized block design.The mice were given drinking water including different iodine doses which were 50μg/L,250μg/L,500μg/L,1 000μg/L,1500μg/L,2 000μg/L,3 000μg/L respectively.After being fed 100days,the absolute and relative weight of thyroid,goiter rate,the thyroid morphology and serum thyroid hormone level were observed.Results The positive correlation was observed between the absolute and relative weight of thyroid,goiter rate and different iodine doses.And the absolute and relative weight of thyroid in 250μg/L group was significantly different from that in 50μg/L group.Yet,the goiter rate in 500μg/L group was different from that in 50μg/L group.Zero correlation was observed between the level of serum TT₃ and different iodine doses,the positive correlation was observed between the level of serum TT₄ and different iodine doses,and serum TT₄ level in 3 000μg/L group was significantly higher than that in 50μg/L group.Yet serum FT₃ level showed negative correlation tendency,which had not found statistically differnet,but serum FT₃ level in 3 000μg/L group was remarkably higher than that in 50μg/L group.The thyroid morphology is colloid goiter,and with iodine dose increasing,the follicular epithelial cells gradually become thallus,the nuclear become shuttle,the cavity of follicle gradually spread,colloid content gradually increasing.Conclusion The positive correlation was observed between the morphology,thyroid function in mice and iodine doses ranging from 50 μg/L-3 000μg/L,and that the dose of iodine was 250μg/L could result in colloid goiter.