As the Marine resources explores from offshore to the deep sea,the demand for ship steel gradually develops to medium thickness. Thus, the requirment of welding technology which account 30%-50% time and cost of ship and ocean engineering equipment manufacturing are more strict. And the high-efficiency, energy-saving and environmental ship welding technology has become the priority of the shipbuilding industry. In this paper, the processing characteristics, application and research status of various welding technologies medium thickness ship steel are compared. Meanwhile, their development trend are also comprehensive analysis in the aspects of arc welding technology, submerged arc automatic welding technology, gas shielded welding technology, friction stir welding technology and laser welding technology. The research shows that the weld cracks and high residual stress of welded joints are inevitable possess in the actual welding production of medium ship steel, because of the increasment of the crack sensitivity and thickness of ship steel materials. In order to realize the development of automatic, efficient, green, reliable and intelligent welding technology for medium thickness ship steel, laser composite welding technology should be developed