The effects of corona discharge on the particle trajectories in stagnation flow were visualized by laser sheet. At lower cross flow velocities, void was created between corona wire and precipitation plate due to electron avalanche and electrostatic field in the vicinity of corona wire. As applied voltage was increased, corona wind velocities also increased and this fast corona wind makes ambient flow orient to the corona wind, so void width narrows. At higher cross flow velocities, void width was narrowed because particle inertia was large. Particle deposition mass was measured by detaching precipitation plate from wind tunnel. To determine the relative concentration of aerosol seed material in the inlet of wind tunnel, light scattering method was used. As applied voltage was increased, relative deposition rate was increased due to increased particle charging. Relative particle deposition rate was decreased as cross flow velocities increased. This is because in our test conditions Stokes numbers are so low that inertial deposition was negligible compared with that of electrostatic. In conclusion, we could recommend impaction electrostatic precipitator should be effective in larger Stokes number flows conditions.