Abstract: A method for testing energy efficiency of a display device having automatic brightness control (ABC) and local dimming functions includes the following steps: S1: executing an estimation program to obtain an estimation value of on-mode average power consumption of the display device; S2: when the estimation value is greater than or equal to a threshold value, adjusting a turn-on preset brightness value, first brightness adjustment ratios, and/or second brightness adjustment ratios to cause the estimation value to be less than the threshold value; and, S3: when the estimation value is less than the threshold value, actually measuring the display device to obtain a measurement value of the on-mode average power consumption of the display device.