The embodiment of the present invention provides a mask plate and a method of patterning using the mask plate, the mask plate comprising a light shielding area and an opening area, the edge of the opening area being in a concave-convex shape. The embodiment of the present invention, by setting the edge of the opening area of the mask plate in a concave-convex shape, can improve linearity of the matrix edge formed after the processes of coating, exposing, developing, roasting of the photoresist, so as to prevent the problem of generating a jagged or a wavy shape at the matrix edge of a color filter in a color film substrate, thereby improving uniformity of color display of a liquid crystal display. The effect is particularly significant for a product using a negative photoresist or with a relatively thin line width in the formed matrix.