Abstract: For better understanding of the plasma physical mechanism in the discharge chamber, the discharge chamber of Kaufman ion thruster was researched numerically, the primary electrons are treated as particles and the secondary electrons and ions are described with drift-diffusion model. The numerical results are compared with the given experimental data, showing that: the computational method suits the numerical research of the plasma flow rules in the discharge chamber; the plasma flow distribution and evolvement rule are obtained in the steady state, which agree with the experimental measurements; primary electrons are restricted distinctly by the design of magnetic field, of which the probability of ionization collision with propellant gas is increased effectively; precise description of s