The invention discloses a camera focusing method for acquiring high quality document images and a device and can realize accurate focusing of a focusing lens. The method comprises steps that S1, during automatic camera focusing, multiple preview low resolution images are acquired through changing front and back positions of the focusing lens of a lens group; S2, an image of the multiple preview low resolution images having the largest confidence is selected and is taken as an optimal image, and the position of the focusing lens corresponding to the optimal image is taken as an optimal focusing position of the focusing lens; and S3, the position of the focusing lens is adjusted to be the optimal focusing position, and thereby the camera can be used for shooting intelligible high quality images.