Abstract: The present invention discloses a non-hysteretic oxygen supply respirator system, comprising a respiratory mask, an inhaling pipe, an exhaling pipe, an oxygen supply chamber, an auxiliary oxygen supply pipeline, and a start-stop cylinder for opening and closing the auxiliary oxygen supply pipeline. The non-hysteretic oxygen supply respirator system in the present invention supplies a small amount of oxygen during the second half of exhaling by providing the auxiliary oxygen supply pipeline, so as to compensate for the amount of oxygen required by a user during the hysteretic time after the respirator senses the inhaling airflow, avoid the situation that the user inhales laboriously due to the hysteresis of inhaling oxygen supply, and give the user a better respiratory experience. The start and stop of the auxiliary oxygen supply pipeline are controlled by the airflow of the exhaling pipe, making the control simple and convenient and the exhaling smoother.