Objective To reveal the relationship between the iodine nutrition and the change of spectrum of thyroiddiseases by analyzing the change of spectrum of thyroid diseases in different iodine environments before and after the implementation of universal salt iodization （USI）. Methods To compare the urinary iodine concentration between the normal people （1 000 cases） and the patients with thyroid diseases （5 998 cases） by surgical operations who were from 4 cities of Guangxi Zhuang Autonomous Region， covering the iodine deficient areas and the iodine rich areas. Results After the USI was put into practice， the proportions of nodular goiter decreased， but the proportions of toxic nodular goiter， thyroid papillary carcinoma， and Hashimoto thyroiditis were higher than those before USI （P＜0.05）. The urinaryiodine concentrations of nodular goiter， Graves disease， toxic nodular goiter， thyroid papillary carcinoma， and Hashimotothyroiditis were higher than those before the measure was taken （P＜0.05）. The urinary iodine concentration of patients with thyroid was higher than that of normal people （P＜0.05）， and the urinary iodine concentration of patients with thyroidand normal people was higher than those before the USI （P＜0.05）. Conclusions The change of spectrum of thyroid diseases in Guangxi Zhuang Autonomous Region is obvious within 10 years after USI had been taken. The excessive intake of iodine may be one of the dangerous factors leading to toxic nodular goiter， thyroid papillary carcinoma， and Hashimoto thyroiditis.