The purpose of this study was to develop an automatic bronchial aspiration system to minimize tracheal mucosal damage in ventilator patients. Operation performances of the system's suction pressure, bronchial intubation depth, suction cycle, and tube cuff pressure were tested. To check the clinical results, subjects underwent endoscopy after applying the previous manual method for 24 h. After that, they underwent endoscopy after applying the proposed suction system for 24 h. For quantitative evaluation of test results, the tracheal mucosal injury was divided into the following five grades: grade 0 = normal, grade 1 = erythema or edema, grade 2 = erosion, grade 3 = hemorrhage, and grade 4 = ulcer or necrosis. In the performance test, an error of up to 12 mmHg occurred within the normal operation error range for suction pressure control. The insertion depth control had a maximum error of 7.0 mm within the normal operation error range. On the other hand, there was no error in the time control or the tube cuff pressure control. In the clinical trial, after using the proposed system for five subjects to find changes in tracheal mucosal injury by endoscopy, reduced injury or no change in injury was found. The system proposed in this study is confirmed to be able to remove the sputum while minimizing tracheal mucosal injury that can occur while using the previous manual suction device.