The invention discloses a brightness adjustment method for displays, comprising: extracting environment brightness data from the digital image information captured by camera device; according to a preset relationship between environment brightness and display brightness, judging if the prior brightness of a display is corresponding to the adjusted environment brightness data, and when they are not corresponding, adjusting the brightness of the display to the value corresponding to the environment brightness. The invention further discloses a display brightness adjuster and a computer, which can on-timely and effectively adjust the brightness of displays according to the change of environment brightness.