Abstract: In order to measure the luminance uniformity through the projection lens at the position of the film, an image luminance measurement method was used. The relative brightness distribution of the whole irradiated surface was obtained by using the image luminance measurement method which was more convenient and economical than the traditional method by using light radiometers or photocells. The non-uniformity measured by image luminance measurement method was 4.24%, while the non-uniformity measured by light radiometers was 3.92%, and the relative error was only 8.16%. This method can be applied to solar simulator uniformity measurements and venues uniform illumination detections.