1. A model experiment was pergormed just as in the case of a real wound occurrred in the lung. The air leak changed according the diameter of the opening, the difference of the pressure and the expansion of the the bag. 2. Three bottle catheter suction drainage consisting of a trap bottle, water seal and valve bottle in series was used as Theaspiration apparatus. By animal experiment, the air leak mostly continues 7 hours to 12 hours after the operation. 3. The appropriate pressure of the intermittent insufflation for the re-expansion is +15cm H(2)O. This insufflation does not injure the surface of the wound and the parenchyma of the lung. 4. By the intermittent insufflation after the segmental pneumectomy, the air leak continues for about 6 hours, and it showe better re-expansion more earlier than the non-insufflation. 5. Testing the air leak by cutting the bronchus in different thickness, the air leak stops around 6 hours with the 0.1cm diameter one but takes more than 30 houts with 0.3cm one. 6. The air leak and the insufflation have important influence upon the intrathoracic pressure, and by the massive air leak the re-expansion of the lung is much slower.