The most common disorder of sleep apnea in children is obstructive sleep apnea syndrome (OSAS), characterized by interrupted breathing and partial or complete obstruction of the upper airway, the main factor is the enlargement of the tonsils and adenoids in the pediatric pharynx. The clinical symptoms are snoring, and open-mouth breathing, then resulting in hypoventilation and hypoxemia. Due to the age of children, tonsillectomy and adenoidectomy are often performed under general anesthesia with tracheal intubation. The risk of hypoxemia and the degree of oxygen saturation reduction are bigger when the mask was removed in the supine position, and the most serious complication also occurred in the supine position. Therefore, the lateral position is preferable to the supine position for mask removal. There are few reports on the effect of different positions on complications related to tracheal extubation after tonsillectomy and adenoidectomy under general anesthesia in children with OSAS. In this study, we will investigate and compare whether the use of lateral position or semi-prone position impact on the occurrence of choking, agitation, decreased pulse oxygen saturation - (SpO2) and the oral and nasal secretions during the awakening period.