Welding machine based on visual localization and automatic welding method

The invention relates to a welding machine based on visual localization. The welding machine comprises a base, a movement mechanism mounted on the base, a welding gun module connected with the movement mechanism and a visual localization module, wherein the visual localization module comprises an image acquisition module which is fixedly connected with the welding gun module and is used for acquiring image information of a workpiece to be welded, an illumination module which is matched with the image acquisition module and is used for illuminating the workpiece to be welded, a reference objectwhich has a determined coordinate value, is arranged between the workpiece to be welded and the image acquisition module and is located in a photographing range of the image acquisition module, and an image processing device which is connected with the image acquisition module and is configured to identify and acquire a characteristic pattern in an image, compare the characteristic pattern with the coordinate value of th