The alignment effect of liquid crystals on Polyimide surfaces bombarded by a low energy argon ion beam and the effect of pretilt angle on viewing characteristics of an LCD cell are discussed. The unidirectional out-of-plane liquid crystal tilt angle is varied with various ion beam irradiation conditions, such as the energy of the incident ions, the angle of incidence and exposure time. As low pretilt angle is profitable for wider viewing property, LCD cell with ion beam modified Polyimide layer show wider viewing characteristics.