The trend of the welding technology of lightweight alloys such as aluminum alloy and magnesium alloy has been studied. The lightweight alloys in the automobile, high-speed light aircraft and modern aerospace industry can reduce vehicle weight, while stringently demanding the high quality and efficienct welding techniques, to produce the best weldments. Among the production technologies, welding plays an important role in the fabrication of lightweight vehicle structure. This has led to an increasing attention towards the use of modern welding technology such as laser beam welding process, ultrasonic welding process, friction stir welding technology and laser hybrid welding technology, etc. This paper covers the recent technical trends of welding technologies of lightweight alloys including the COMPENDEX DB analysis of welding metallurgy, welding process, and welding fabrications.