A method of forming pixel cell for three-dimensional image display is provided. The method of forming pixel cell according to this invention relates to a method of forming pixel-cell in a three-dimensional image display system including an image display panel in which a plurality of unit patterns are arranged in a vertical direction and horizontal direction and an optical plate having repetitive pattern. The method according to this invention comprising regarding each side of rhombus pattern having an arbitrary vertex angle as a straight line having a predetermined slant; calculating a number of unit pattern in vertical direction and a number of unit pattern in horizontal direction, corresponding to said predetermined slant; approximating said predetermined slant to stepped patterns with said number of unit pattern in vertical direction and said number of unit pattern in horizontal direction; and forming said pixel cell using said stepped patterns. And integer-numbered unit patterns are arranged in said pixel cell. By the present invention, quality degradation of a three-dimensional image due to Moire patterns is reduced.