This study uses an magnetohydrodynamics (MHD) model to simulate unsteady one-dimensional transport variables in argon plasma, under low pressure and weak ionization between two planar electrodes suddenly biased by a negative voltage or electric field. Plasma has been widely used in etching, ion implantation, light source, and nuclear fusion, etc. Studying transport processes of plasmas therefore is important. Ignoring magnetic field, collisions between ions and electrons, the computed results in this work shows density, velocity, voltage, electric field, energy and temperature transport phenomenon in different cases. The results give insight by theory and simulation the surfaces behavior in plasma. Keywords: magnetohydrodynamics (MHD), transport variables in sheath,space charge