Abstract: Holographic surface relief gratings were employed as the orientation layer for liquid crystal display.The influence of liquid crystal thickness on the alignment of liquid crystal on gratings are analyzed.When the thickness of the liquid crystal layer is about 8 μm,uniform texture is formed and the liquid crystal molecules align along the grooves of the gratings,the transmitted light intensity changes periodically as the gratings rotated 90^o.Period grating is the main reason for liquid crystal uniform alignment.