Objective To investigate the feasible safty of the subtotal thyroidectomy on the condition that hyperthroidism is accompanied with cardiothyotoxicosis. Methods In 138 hyperthroidism cases accompanied with cardiothrotoxicosis, the operation tolerance was evaluated preoperatively with a dagrous index of hyperthroidism accompanied cardiothrotoxicosis for operation. These patients were monitored and the dangerous factors were treated preoperatively, to make the operation safely. Results The cure rate that hyperthyroidism with subtotal thyroidectomy was 100%. The cardiothrotoxicosis cure rate was 89.2%. The cardiac insufficiency and operative complication didn't occur in any patient. Conclusions Hyperthroidism accompanied with caridiothrotoxicosis isn't of intraindaction to subtotal thyroidectomy. The operation is safe and effective after controlled the dangerous index.