Abstract: The evaluating norms of excimer laser beam uniformity are analysed in detail. The process window defines uniformity requirements of the excimer laser,while the energy fraction answers the problem of useful percentage of energy within a giving process window. The top-hat factor defines the uniformity of the whole energy range, and the dynamic range is the variation range of screen-homogeneity in the specific application. The beam uniformity obtained by different beam homogenizer is compared by using CCD laser beam analyzer. With the fly's eye homogenizer, energy untilization ratio is high and the homogeneity of the whole light spot is fine, but the dynamic range of the screen-homogeneity is narrow; The prisms has wide dynamic range but bad homogeneity.