Device and method for scanning an object outline image are provided. The scanning device includes a light source, an optical sensor and a processor. The scanning method includes: providing a polarized projection light beam; projecting the polarized projection light beam to an object, and correspondingly reflecting a polarized reflection light beam by the object according to the polarized projection light beam; capturing an image of the polarized reflection light beam; calculating polarization state of target according to the polarized projection light beam and the polarized reflection light beam, the polarization state of target having a plane angle from normal projection and a corresponding point position; and restoring an outline image of the object according to the polarization state of target.