Abstract: The double-break molded case circuit breaker has the characteristics of fast breaking and double-arc motion. In view of the current lack of research on the discharge phenomenon of breaking double arcs, it is of great significance to explore the arc dynamic behavior of double-break breaking. Based on the theory of magnetohydrodynamics and the actual size of the arc extinguishing chamber of the circuit breaker, this paper constructs a multi-physical field coupling breaking double-arc simulation model, analyzes the dynamic evolution behavior of the arc and the breaking characteristics of the circuit breaker, and explores the gas flow phenomenon and arc movement mechanism of the arc extinguishing chamber during the breaking process. The test platform is built to carry out the breaking test, and the simulation and test results are compared. On this basis, the simulation analysis of the influence of the arc-driven magnetic field and the concentration of the ablated metal vapor on the breaking double-arc characteristics is carried out. The results show that under the synergistic action of the airflow field and electromagnetic field, the broken double arc undergoes arc growth, arc root transition and arc column cutting to finally complete the arc extinguishing. Compared with the arc current and arc voltage curves, the simulation results are consistent with the experimental results. In addition, the arc-driven magnetic field has a positive effect on the arc extinguishing process, but this effect shows a non-linear positive correlation, and the effect is more significant at lower magnetic field strength. The existence of iron vapor significantly changes the shape and trajectory of the high-temperature arc column. Compared with high concentration, low concentration of iron vapor is more effective in inhibiting the growth of arc pressure and delaying the decline of arc current. It is of great significance for the structural design and performance improvement of circuit breakers to explore the dynamic evolution law and breaking characteristics of breaking double arcs.