Lean is a basic concept to improve the management and technology level in SAMC since 2003. This text use the lean tools like Situation-At-A-Glance、Time study and so on, to count data and layout the production line of cargo door frame program. Through the"U"design, this text also enhance the lean management to improve the tooling, finish the paperless, send the parts to the work area, through which to optimize the production line.