Abstract: The power supply module shell of certain product is actually a kind of rectangular box part of drawing-style with high requirement for dimensional accuracy and appearance quality．As per conventional process planning，it can be formed merely on the special punching equipment after many machining procedures．On the basis of thorough computations and analysis of the technological parameters，a constant-force drawing ＆trimming compound die dedicated for this rectangular box part is designed according to the existing machining conditions．Since the die employs a special mechanical structure to implement constant-force edge formation during drawing process on the ordinary press machine，the drawing process requirement can be satisfied properly．In addition，extruded edge-trimming with a relatively high accuracy on the part can be achieved at the end of the drawing stroke so as to improve the work efficiency，reduce the cost and meet the requirement of small-lot production．