We investigated the cause of liquid crystal alignment when an ion beam is irradiated to the liquid crystal(LC) alignment film for liquid crystal alignment. We investigated liquid crystal alignment in response to changes in ion beam (IB) incident angle and electro-optical (EO) properties of twisted nematic (TN)-liquid crystal displays (LCDs) on polyimide (PI) surface. X-ray photoelectron spectroscopy(XPS) analysis showed that the C=O chemical bond strength decreased with changes in the IB incident angle, while the C-O chemical bond strength increased. Therefore, it was found that the dipole-dipole interaction between C-O chemical bonds and LC molecules has a chemical ordering effect. Good and uniform alignment of nematic LC was observed on the liquid crystal alignment layer surface by IB irradiation, and good EO properties of IB aligned TN-LCD were achieved on the liquid crystal alignment layer surface.