Abstract: The TRAb content of the thyroid diseases 758 cases (including the first visit thyroidism group 166 cases; the thyroidism group with normal thyroid function by mesicine treatment 198 cases, the group with abnormal thyroid function by medicine treatment 86 cases, the group with lower thyroid function 24 cases, the group with normal thyroid function by 131 I treatmnt 104 cases, the subacute thyroiditis group 48 cases, the simple goiter group 52 cases, the primary hypothyroidism group 80 cases) and the normal control group 62 cases are detected. The results show that the values of TRAb are much higher in the groups with normal or abnormal thyroid function by medicine treatment, the group with lower thyroid function, the group with 131 I treatment and the group with primary hypothyoidism than that of control group ( P <0.01). The values of TRAb are normal in the groups with subacute thyroiditis and simple goiter compared with control group ( P >0.05). The differential of the TRAb average and positive rate is obvious between the groups with normal and abnormal thyroid function by medicine treatment ( P <0.01), as well as between the groups the normal thyroid function by medicine and 131 I treatment ( P <0.01). The TRAb levels in serum are higher in the patients with thyroidism and primary hypo thyroidism, and the TRAb levels are normal in the patients with subacute thyroiditis and simple goiter. So, TRAb is a auxiliary index in the diagnosis of thyroidism and hypo thyroidism and also a differential diagnosis index about the thyroidism and subacute thyroiditis. At the same time, TRAb is an important index in evaluating the autoimmune monitoring function of the body, and stopping the use of thyroid medicine.