Abstract: Introduced in the article are such manufacture processes for large-sized straight welded tubes as the UOE process, the roll-bending process, the innovative die-pressing process and the innovative folding process. It is found that although the equipment, product range, production scale and initial investment vary with different process,product quality is almost the same. For mill type selection by domestic firms, comprehensive consideration of the country's own circumstances should be taken due to the fact that large-sized straigbt welded tubes are mostly used in pipeline construction and the market thereof fluctuates periodically.