Objective:To investigate the relationship between iodine nutrition level and thyroid disease.Methods:Totally 299 patients with thyroid disease who were treated at Shandong Provincial Institute for Endemic Disease Prevention and Control from 2016 to 2018 were selected as case group which was further divided into Graves' disease group (GD group, 137 patients), chronic lymphocytic thyroiditis group (HT group, 90 patients) and thyroid nodule group (72 patients). At the same time, 75 healthy people with no history of thyroid disease, normal thyroid color ultrasound and thyroid function were selected as control group. Morning urine was collected and urinary iodine was detected by arsenic cerium catalytic spectrophotometry. Fasting venous blood was extracted, and serum levels of thyroid stimulating hormone (TSH), free triiodothyronine (FT 3), free thyroxine (FT 4), thyroid globulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) were detected by electrochemiluminescence method. Results:The difference of median urinary iodine in the 4 groups was statistically significant ( H = 42.530, P < 0.05). The medians urinary iodine in GD and HT groups (326.79, 341.91 μg/L) were higher than those of thyroid nodule group and control group (235.01, 187.32 μg/L, P < 0.05). The levels of TSH, FT 3 and FT 4 in GD group were compared with those of control group, and the differences were statistically significant ( P < 0.05). The positive rates of TgAb and TPOAb in HT group were significantly higher than those in GD, thyroid nodule and control groups, and the positive rates of TgAb and TPOAb in GD group were higher than those in thyroid nodule and control groups ( P < 0.05). Conclusions:GD and HT patients have excessive iodine nutrition, and high iodine intake may lead to the occurrence of these thyroid diseases (GD and HT). Thyroid function test combined with laboratory urinary iodine test can be used to diagnose thyroid diseases simply and quickly.