A system and method for positioning a portion of an object to be measured includes installing a digital camera adjacent to a charge coupled device (CCD) lens of an image measuring machine, setting positioning parameters corresponding to different positions of the digital camera on a Z-axis of a world coordinate system, receiving an image of the object captured by the digital camera, and selecting corresponding positioning parameters according to a position of the digital camera. The method further includes selecting a point of the portion of the object in the image, calculating coordinates of the selected point in a plane of the CCD lens, and controlling the CCD lens to move to the calculated coordinates so as to position the CCD lens on the portion of the object.