The invention discloses a system for continuous monitoring of radioactive inert gas in ambient air. The system includes a sucking pump used for sampling, a drying pipe connected with the sucking pumpand used for separating H2O and CO2 in components, a first subsystem used for separating O2 in the components, a second subsystem used for separating N2 in the components, a third subsystem used for further separating N2 in the components, a fourth subsystem used for temporary storage of gas and a fifth subsystem used for performing component separation which are connected in sequence, and the monitoring system also includes a thermal conductivity detector used for performing gas component monitoring and a radionuclide activity and concentration detection component connected with the thermal conductivity detector. The system for continuous monitoring of radioactive inert gas in ambient air adopts a beta-ray measurement mode, is high in detection efficiency and is accurate in measurement; the temperature is proper in the whole measurement process, compared with traditional sample preparation through a deep cooling method, the system has the characteristics of being easy and convenient to operate and being safe and stable; and the thermal conductivity detector is applied to the whole separation process of gas components, and a gas separation stage can be monitored in real time.