Abstract: Objective To study the function of a new shape closed thoracic drainage tube. Methods A Y shape closed thoracic drainage tube was made with medical silica.Routine thoracoscopy was performed in dogs under local anesthesia through the "Y" shape closed thoracic drainage tube.Changes in heart rate,blood pressure,oxygen saturation and partial oxygen pressure of dogs were compared. Results Routine thoracoscopy could be easily completed in dogs under local anesthesia through the Y shape closed thoracic drainage tube.No significant difference was found in heart rate,diastolic blood pressure and respiratory rate of dogs with open and controlled closed pneumothorax（P＞0.05）.However,the systolic blood pressure of dogs with open pneumothorax was higher and their oxygen saturation and partial oxygen pressure were lower（P＜0.05）. Conclusion The Y shape closed thoracic drainage tube can be used in routine thoracoscopy under local anesthesia instead of the special flexible trocar for LTF-240 thoracoscope（Olympus,Tokyo,Japan）,thus having a good prospect.