Abstract: Mechanics characteristic for deep-drawing process of panel parts is analysed by upper-bound method. With the stress and strain rate distribution in the flange must being continuous，it cause that a great many particles of circular angle area flow into straight side area in the deep-drawing process of panel part. Therefore，the transition region forms between a circular angle area & straight side area, where the flow resistance is of maximum. This is a essential mechanics characteristic in the deep-drawing process of panel parts. It is a key technology to improve the forming ability of sheet metal that flow resistance in the transition region is decreased with a designed process measures.

Key words: Deep-drawing, Flow resistance, Mechanics characteristic, Transition region