An image processing method and an image processing device are provided. The image processing method includes the following steps. A light source is projected onto a 3D model via a plurality of projecting locations to generate a plurality of facial shadow pictures. The facial shadow pictures are superimposed to generate a composite shadow picture. An eye-eyebrow location, a nose location and a mouth location in a 2D facial map are obtained by way of analyzing according to the composite shadow picture. A plurality of characteristic points are calculated according to the eye-eyebrow location, the nose location and the mouth location in the 2D facial map.