A scanner lens includes a first lens, a second lens, and a third lens. The first lens is provided with a first focal length. The first, second, and third lenses are sequentially arranged from an object end to an imaging end and are respectively provided with a plus diopter, a minus diopter, and a plus diopter. At least one of the first, second, and third lenses comprises an aspheric lens. The ratio of the first focal length to a system focal length of the scanner lens ranges between 1 and 2.