The present disclosure provides a brightness control method and a terminal device. The brightness control method includes: when confirming switching from a first mode to a second mode, adjusting a brightness of a first area of a screen of the terminal device from a first brightness to a second brightness; where the first brightness is the brightness of the first area in the first mode, and the first brightness is different from the second brightness; and, after entering the second mode, setting a brightness of a second area of the screen to be a third brightness. After entering the second mode, the brightness of the first area is the second brightness.