Airway perforation is a rare but potentially fatal complication following laser surgery. A 66 years old man was admitted for surgery of tracheal stenosis. He had undergone 2 prior anesthesia for similar surgery and had diabetes mellitus due to chronic steroid therapy. 2 hours after surgery, tracheal perforation lead to pneumomediastinum, tension pneumothorax and perforation of innominate artery with potential risk to injury, which lies in the close proximity to perforation site of trachea. Arterial wall was so weak and fragile that it was difficult to repair the ruptured site. During the procedure, hemorrhage persisted and cardiac arrest developed. Immediate CPR(cardiopulmonary resuscitation) with internal cardiac massage was done but the patient did not recover. We believe that in patient with history of multiple operations, chronic steroid therapy and diabetes mellitus, the vascular structure of thin and fragile should be approached with greater caution when using CO2 laser during surgery.