An image capturing device and a digital zooming method thereof are proposed in the invention. The method includes the following steps. A scene is captured by a primary lens and a secondary lens to generate a primary image and a secondary image. Image rectification is then performed on the primary and the secondary images to obtain two corresponding rectified images. Feature points detected and matched from the two rectified images are used to determine a corresponding overlapping region, respectively. Pixel displacement and depth map in the two overlapping regions could be calculated and estimated. Image zooming and warping techniques are performed on the two rectified images to obtain corresponding warped images using a recalculated homography matrix according to each specific zooming factor. Finally, the two overlapping regions in the warped image are fused by a weighted blending approach to generate a digital zoomed image.