A printing method for a 3D printer is present. After opening a 3D model, the method divides the 3D model into several area objects which are separately corresponding to different areas of the 3D model being formed on a forming platform of the printer. When executing printing procedures, the method firstly determines a lowest area object of the several unfinished area objects. Then, a nozzle array of the 3D printer is controlled to move to upon an area according to the determined area object, and to jet ink upon the area for stacking the determined area object. After the determined area object is stacked completely, the nozzle array is then controlled to move to other area and stack other area object.