The invention discloses an optical compensation method and device for a display panel, and a display device, so as to enable the brightness difference between pixels of the display panel at the same gray scale to be reduced, to improve the brightness uniformity of the display panel, and to improve the display quality of the display panel. The method provided by the invention comprises the steps: determining a preset brightness compensation parameter corresponding to a preset gray scale section where a target pixel of the display panel under the drive of the current gray scale belongs; and carrying out the adjustment of the brightness value of the target pixel according to the brightness compensation parameter.