The invention discloses a method and a device for forming plates through gradual approximation bending on a three-dimensional
numerical control plate bending
machine (1). The method comprises the following steps of: performing targeted iteration gradual approximation bending by utilizing a resilience rule of a plate (5), comparing a shape of an actually formed curved surface B of the plate (5) subjected to pressing resilience with a shape of a theoretical target curved surface S through online measurement, and setting an approximation bending pressing curved surface C for limited approximation pressing according to an error offset value h after resilience. By the device, an online
laser three-dimensional coordinate
measuring instrument (4) connected with a computer is arranged on the three-dimensional
numerical control plate bending
machine (1). Complex mechanical calculation is not needed, the problem of bending resilience of a ship plate can be rapidly solved on line in real time, as long as the approximation bending pressing is performed for 1 to 3 times generally, the requirement on
machining accuracy can be met, the problem of resilience of a numerically controlled bent plate is rapidly and effectively solved, the forming accuracy of a three-dimensional curved surface ship plate is guaranteed, and the method and the device have simple and rapid effects.