1. An image fusion method for multiple lenses, adapted for an image fusion device with a plurality of lenses, and the image fusion method comprising: taking a plurality of parallax images with different focal distances through the lenses; analysing a plurality of feature points of the parallax images; calculating matching relationships among the feature points of the parallax images; moving each parallax image according to the matching relationships, to adjust a same image portion of each parallax image to a same image position; and fusing the moved result of the parallax images, to generate a fusion image; wherein in the step of moving each parallax image, further comprises: selecting one of the parallax images as a primary image, and the same image portion of the primary image being located on the image position; calculating a movement quantity of each unselected parallax image according to the matching relationships, wherein the movement quantity is related to a distance of the same image portion of the corresponding parallax image moving to the image position; and moving the corresponding parallax image according to each movement quantity.