Abstract: In this paper, the uphill welding and downhill welding tests were carried out on workpieces with different dip angles under the same MAG welding parameters by single factor test method. The characteristic parameters such as edge and size of the molten pool were extracted by High speed camera and image processing technology and the area and rear drag angle of the molten pool was corrected. The influence of workpiece dip angle on weld pool width, length, area, rear drag angle and weld forming was analyzed. The results show that when the dip angle of the workpiece exceeds 30°, the obliquity of the workpiece has obvious influence on the morphological characteristic parameters and the size of molten pool and it is different in uphill and downhill welding. It is of great significance to reduce welding defects and improve welding process in non-horizontal position welding.