1. A printing system, comprising: a light source unit, configured to illuminate a target object; at least one image-capturing module, comprising: an image-capturing unit, disposed at a side of the target object; and a focus-adjusting lens group, disposed between the image-capturing unit and the target object; a processing unit, controlling the focus-adjusting lens group to change shooting focal lengths and controlling the image-capturing unit to capture a plurality of images of the target object under the different shooting focal lengths, wherein each of the plurality of images comprises a focused local image and an unfocused local image therein, and the processing unit calculates a three-dimensional profile data of the target object by arranging the focused local images among the images based on the shooting focal lengths corresponding to the focused local images; and a printing device, printing a plurality of cross-sectional profiles of the target object according to the three-dimensional profile data, wherein the processing unit maps the three-dimensional profile data to a driving unit of the printing device by respectively mapping the focused local images among the images of the target object captured by the image-capturing unit under the different shooting focal lengths to the driving unit of the printing device, and the driving unit drives the printing device to print out, layer by layer, the plurality of cross-sectional profiles of the target object in a cumulative and stacked manner according to the mapped corresponding focused local images among the images.