Hyperthyroidism crisis is a rare complication of pregnancy, which is prone to occur on untreated or poorly treated thyrotoxicosis patients, with a fatality rate up to 20%. The pathological mechanism is not clear, but it may relate to the stress state of pregnant women during delivery and the perioperative period of cesarean section. Hyperthyroidism crisis in pregnancy, especially occurs during delivery is critical and difficult to identify, which makes diagnosis and treatment very intractable. Thereby, early identification and prevention are very important.