The depth of transoral insertion of tracheal intubation in adult females is usually about 21-25 cm, which generally correlates with the patient’s height and weight. The depth of transoral tracheal intubation is related to gender and height, weight, etc. According to the standards of clinical anesthesiology, the depth of intubation for adult males is about 23 cm from the incisors to the head end of the tracheal tube, and the depth of intubation for adult females is about 21 cm, and the inner diameter of the tracheal tube for adult females is usually No. 6.5 or 7, and that for males is usually No. 7 or 7.5, but it will be determined according to the actual condition of each patient due to the individual variability. The size of the tracheal tube is usually 6.5 or 7 in adult women and 7 or 7.5 in men. Transoral intubation is an important means of clinical rescue of critically ill patients or clinical anesthesia, through the tracheal intubation can be relieved of respiratory obstruction, to maintain a smooth airway, mainly for respiratory failure, cardiac arrest, respiratory muscle weakness and other critically ill patients. Orotracheal intubation should be operated by a doctor, please do not operate it by yourself, in order to avoid serious adverse consequences of improper operation.