A method for displaying a preview image, includes: obtaining a real-time image collected by an imaging device of a mobile terminal without turning on a flashlight; determining at least one target area in the real-time image; determining a distance between the mobile terminal and an entity corresponding to each of the at least one target area; determining a brightness enhancement degree for each of the at least one target area respectively according to the distance corresponding to each of the at least one target area and a flashlight parameter of the mobile terminal; and performing brightness enhancement on each of the at least one target area respectively according to the brightness enhancement degree for each of the at least one target area, and displaying the brightness-enhanced real-time image as a preview image.