Objective：This study aims to analyze the types of hyperthyroidism in pregnancy and to investigate its effects on pregnancy outcomes. Methods：Total 300 pregnant women were enrolled，who were diagnosed as hyperthyroidism in this study. To analyze the types of hyperthyroidism in pregnancy，according to the diagnostic criteria，there were 108 cases in Graves’ disease（GD）group，104 cases in gestationgal transient thyrotoxicosis（GTT）group，and 33 cases in hashitoxicosis group. Then 340 normal pregnant women were selected for control. The changes of thyroid function in pregnancy and its effects on the adverse outcomes of mothers and offspring in different groups were analyzed. Results：Of 300 pregnant women with hyperthyroidism，41.67% had hyperthyroidism before pregnancy and 58.33% were diagnosed with hyperthyroidism during pregnancy. Among 300 women，36.00% were GD，34.67% were GTT and 11.00% were hashitoxicosis. The proportion of pregnant women who have persistent hyperthyroidism was significantly higher in GD group than in GTT group. The incidences of pregnancy-induced hypertension，preeclampsia，preterm birth，and neonatal hypothyroidism were significantly higher in GD group than those in GTT group or in the control group. Conclusion：For women with active GD or previous history of hyperthyroidism，reasonable pre-pregnancy counseling and pregnancy planning are of great significance to reduce the occurrence of adverse outcomes of mothers and offspring.