In order to solve the problem of lightning damage in catenary of high-speed railway,a combined multiple-breakpoints arc-extinguishing lightning protection gap device (CMALPGD) for catenary of high-speed railway has been developed.In a bid to verify the feasibility of the arc-extinguishing device,this paper discusses the gas production and arc-extinguishing principle of the device,establishes the three-dimensional dynamic magnetohydrodynamics (MHD) model of arc of arc-extinguishing chamber.Through the COMSOL Multiphysics simulation software,the temperature,conductivity and high-speed airflow velocity (maximum speed of 1000m/s) of the arc at the break of the arc-extinguishing chamber were analyzed during the CMALPGD operation.It is verified that the high-speed airflow can act on the arc and extinguish the arc.The entire arc-extinguishing time is about 2.5ms.At the same time, the test circuit was built for arc-extinguishing test, and the arc-extinguishing time under the test conditions was 3.0ms and the arc did not re-ignite for a period of time. The simulation and test results are almost the same, which fully proves the possibility of applying CMALPGD to catenary of high-speed railway.