Abstract: The coat-hanger die has been widely used in melt-spun nonwoven production line.Nevertheless it is lack of theoretical evidence for design.This paper provided the design theoretics of the die fluid channel based on the theories of fully developed flowing models with non-Newtonian fluid flowing in the circular conduit and in the slot,to realize uniformly distributed flux,equivalent pressure drop and equal retention time at the die exit across the die breadth.Besides,the calculating method of forces acting on the die was also upbuilt and the melt channel design was discussed too.The design theoretics,validated by the evidence that the fluid uniformity was considerably improved,provided forceful basis for the innovative design of coat-hanger die.