Abstract: Simulating four conditions of the hair dryer:normal used, electrical superheated, heated in fire after normal used, and heated in fire after electrical superheated, the fire residues of hair dryer were investigated. The microscopic appearances of heating wire were observed by scanning electron microscope. The result indicated that the microscopic appearances in different conditions were not same. Therefore, the state of the hair dryer before fire could be distinguished directly and quickly by observing the microscopic appearances of heating wires. This provided a new technical method for the recognition of fire accident.