Objective:It is more difficult to conduct precision radiotherapy for organs of the human body with the respiratory movement. It is necessary to compensate a certain degree of deviation which is produced by many thoracic and abdominal organs with breathing exercises. To develop a new breathing control system of tumor target for precision radiotherapy is the practical demand in hospital.Methods: According to the current active breathing control system, there are gasbag, control box, handle switch for the patients, computer, automatic gasbag controller, respiratory sensor and communication tools. The Pneumotach PowerCube pulmonary function respiratory sensor and C++ high level programming language were selected to program the breathing control system.Results: The system could make patients conduct respiratory control better, reduce the deviation of pulmonary tumor caused by respiratory movement and improve the accuracy of treatment.Conclusion: The system had a lot of functions, such as dispersion, oscillation, ventilation and so on. It is refitted on the current instruments and successful to clinical application.