Abstract: The development of fluorine-free switchgear is particularly important to the context of "carbon peak and carbon neutrality" goals. In this paper, we use carbon dioxide (CO₂) as an arc-quenching medium for a high-speed earthing switch (HSES), establish the arc mathematical model, carry out the simulation study on electromagnetically induced current interruption of 126kV HSES. The chamber pressure, arc temperature and post-arc dielectric recovery strength of CO₂ are calculated during the breaking process of the HSES with/without air-flowing assisted structure. The influence of cylinder diameter, breaking speed and pressure on the interruption performance of the HSES is analyzed, and the design of the arc extinguished structure of CO₂ is proposed. The results show that compared with the airless blowing and the suction type structures, the HSES with puffer type assisted arc extinguished structure has the stronger breaking capability; by optimizing the cylinder radius, breaking speed and pressure, the breaking capability can be further improved. When the cylinder radius is 45mm, the breaking speed is 2.55m/s and the pressure is 0.8MPa, the HSES with the puffer type assisted arc extinguished structure and CO₂ can break the electromagnetically induced current at the first current zero point. And the post-arc dielectric strength recovery speed is 26.33kV/ms, higher than the standard transient recovery voltage (TRV) of 23.34kV/ms. The model prototype is made, and the induced current switching capability of the prototype is tested to verify the accuracy of the simulation results. The research results can help guid and develop the HSES with CO₂ as an arc-quenching and insulation medium for 126kV gas-insulated switchgear (GIS), which has induced current switching (class B) capability.