Abstract: The discharge characteristics of micro cathode arc thruster (μ-CAT), an advanced electric propulsion device for micro/nano satellites, were experimentally investigated with the lab-built test platform, comprising a high vacuum chamber, gauges/pumps, measurement and control units. The influence of the magnetic field on the distribution of μ-CAT plasma ion current was investigated. The preliminary results show that the magnetic field significantly reduces the expansion angle of plasma plume and increases the axial profile of the ion current. The time evolution of the voltage, current and plasma ion current distribution in a single pulse cycle were measured. In addition, the damages, sputtered by the ion current, on the surfaces of cathode, were also evaluated. We suggest that the ground simulation results may be of some technological interest in design optimization of μ-CAT.