Abstract: A scanning system and method for controlling an aiming light source (7), comprising: an image sensor (4), which sequentially exposes a pixel array through a rolling shutter to acquire an image of the target, the pixel array includes effective pixels (5) and non-imaging pixels (6), the effective pixels (5) are pixels that are actually used for image decoding, and the non-imaging pixels (6) are pixels that are not actually used for image decoding; an aiming light source (7) for projecting an aiming pattern (8) to aim at a target; a control unit (12) for controlling the image sensor (4) and the aiming light source (7), so that the aiming light source (7) is in turned off state during the exposure time of the effective pixel (5), and the aiming light source (7) is turned on during at least part of the exposure time of the non-imaging pixels (6).