the present invention provides a gas absorbing system which comprises : an inlet pipe , a gas accommodating section into which gas enters through the inlet pipe , and a negative pressure exhausting pipe which exhausts the gas in the gas accommodating section to external device by using negative pressure wherein the gas accommodating section comprises a first chamber which is provided with air holes in the side wall for discharging the gas in the gas accommodating section or allowing external air entering the gas accommodating section . the gas absorbing system according to the present invention not only can effectively prevent the system internal gas from discharging directly to environment to endanger the health of patients and medical care personnel , but also can reduce the variation of the pressure inside the system when an abnormal incident occurs , so as to prevent it from influencing the safety of the patient to the most extent .