It is a difficult issue during large diameter long distance pipeline laying process to implement pipeline welding construction under the condition of steep slope. Traditional welding method is of low construction efficiency;meanwhile defects like porosity,slag inclusion & incomplete fusion are prone to be found. Automatic pipeline welding under the condition of 30° longitudinal grade is achieved through improvements in equipment and process parameters. This article analyzes technical difficult points of automatic welding in mountain area and introduces an equipment and techniques designed for automatic pipeline welding in mountain area.Welding test was taken through which it is showed that the welding equipment and welding method is able to adapt to welding under the condition of 30°longitudinal grade. Welding quality is guaranteed while welding efficiency is raised by a big margin.