Disclosed is a display module driving device, comprising a display driving module, driving each of the organic light emitting diodes to emit light; a plurality of light sensors, detecting brightnesses of corresponding light sensors and outputting corresponding actual brightness values; a gray scale brightness conversion module, acquiring a gray scale value of each of the sub pixels in a present display frame and converting the gray scale value into a corresponding target brightness value; a comparing module, receiving and comparing the target brightness value and the corresponding actual brightness value of each of the sub pixels; and a controlling module, controlling the display driving module to drive the organic light emitting diodes to maintain the target brightness value as the actual brightness value is equal to the target brightness value. The display module driving device can effectively solve the problem of the display difference caused by the uneven brightness.