An auto-focusing zoom lens mechanism includes a base unit forming a space; an auto-focusing (AF) lens unit located in the base unit and having a trajectory bar engaged therewith; a zoom lens unit located in the base unit and mounted on the AF lens unit and having a trajectory bar engaged therewith; a cam plate unit engaged with the AF lens unit and the zoom lens unit and provided with an AF trajectory groove and a zoom trajectory groove to receive the trajectory bars of the AF lens unit and the zoom lens unit; and a step motor unit engaged with the cam plate unit to drive the cam plate unit, the AF lens unit and the zoom lens unit moving.