A measuring method and a measuring system are used for measuring contrast of a display device, including controlling the display device to display a first image, measuring brightness of a central area of the first image, controlling the display device to display a second image, measuring brightness of a central area of the second image, and determining the contrast. Both the first image and the second image have a plurality of areas with different gray scales, the first image includes a maximum gray scale area, and the second image includes a minimum gray scale area.