Objective　To observe the effect of high iodine intake on rat's medicine-induced goiter.　Methods　Wistar rats were used for the model of rat's medicine-induced goiter and fed with food of iodine different concentration for seven months,then the extracted thyroid was HE stained and AgNOR stained,the height of thyroid follicular epithelial cell and area of follicle were determined by mapping analysis system.　Results　All the experimental groups of rats had got colloid goiter and the higher the concentration of iodine in food,the lower the height of thyroid cell and the bigger the area of follicles.AgNOR counting of abnormal hyperplasia area in all the experimental groups was increasing.　Conclusions　High iodie intake made the medicine-induced goiter of rats chang into high iodine's goiter and made some area proliferate actively,might change into carcinomas.