We have investigated a photo alignment material for fringe field switching (FFS) liquid crystal display and it has good alignment performance. It realizes alignment by irradiating linearly polarized light with wavelength of 254nm. We have investigated the factors that affect the transmittance in photo alignment FFS mode. The transmittance becomes smaller with the alignment angle increasing. The transmittance is also affected by the L/S width of the ITO electrode, it becomes smaller with the L/S increasing. The LC type also affect the transmittance, we can get higher transmittance using negative LC.