The variation of microscopic parameters of vacuum arc plasma under the action of axial magnetic field isof great significance to the development of vacuum arc and energy change. In this paper

a non-equilibrium state mi-cro model for vacuum arc under the action of the axial magnetic field is established based on the drift-diffusion equa-tion of gas dynamics and Poisson equation of the electric field. The non-equilibrium process of vacuum arc which isfrom a large number of Cu metal vapor is filled with the fracture of liquid arc bridge to the formation of arc plasma issimulated. Collision and recombination of microelectronics

ion and metal vapor molecules with each other in vacu-um arc plasma and other complex changes such as drift and diffusion of particles are also considered here. The lawsof the plasma parameters at the function of different magnetic field strength are analyzed. The simulation results showthat the electric field strength of cathode and anode sheath decreases with the increase of the axial magnetic field

which is advantageous for quenching the arc meanwhile the electrode process is weakened and the density of the elec-trons and the copper ions are reduced

and the electron temperature distribution on the anode surface is uniform andreduced

which is helpful to suppress the increase of the vacuum arc energy.