A focusing method having depth-of-field adaptability and aperture adaptability is provided. The method is applied to an image capture unit. A plurality of first images are captured in an image capture window according to a plurality of objects for obtaining a plurality of distances between the plurality objects and the image capture unit. Thereby, a focus distance of the image capture unit is given. Then, according to a maximum value and a minimum vale of the plurality of distances, the first aperture is adjusted to a second aperture, so that the image capture unit can acquire a complete depth of field by means of the second aperture and the focus distance. Accordingly, the preferred focus distance and depth of field satisfying the requirements for theme or special depth of field can be acquired. In addition, image capturing can be performed for a shorter exposure time.