分析了出口北美市场而生产的地铁车辆的结构特点与影响产品质量的因素 ,介绍了为确保产品质量而开发的 4种自动焊接系统及其相关的新技术 This paper analyzes the structural characteristics of subway vehicles exported from North American market and the factors that affect the product quality. The four kinds of automatic welding systems and related new technologies developed to ensure product quality are introduced