An embodiment of the present invention provides a method and device for adjusting panel brightness, and a screen driving board. The method includes: first dividing a panel to be adjusted into N regions, where N is an integer greater than or equal to 2; and acquiring corresponding RC value of each region in the N regions; adjusting the VGH voltage corresponding to each region according to the RC value of each region, so as to adjust the brightness of each region, wherein the RC value is used to indicate the delay time of the resistor and capacitor, and the VGH voltage is the turn-on voltage ofa gate of a thin film transistor (TFT). The method and device for adjusting the panel brightness and the screen driving board provided by the embodiment of the invention improve the flexibility of image quality adjustment under the condition of ensuring the uniformity of the image quality of a display, and reduce the production cost of the display and the module cost.