Autofocus methods and devices are provided. The method includes: controlling a lens group to move at a first speed, and photographing an image at a preset photographing frequency when the lens group moves at the first speed; when a definition of the image photographed by the lens group in a state of moving at the first speed satisfies a preset condition, reducing a moving speed of the lens group to a second speed, and photographing images at the preset photographing frequency when the lens group moves at the second speed; and when a first image with a highest definition is determined in the images photographed by the lens group in a state of moving at the second speed, controlling the lens group to decelerate, and controlling, when the lens group stops moving, the lens group to return to a position of the lens group where the first image was photographed.