Melt blowing is used commercially as a one-step process for converting polymer resin directly into a nonwoven mat Of microfibers. The inset die is often used to produce polymeric fibers in the melt blowing process. The air jet flow field model for the dual slot inset die is established. The flow field model is solved by using the finite difference method. The numerical computation results Of the air velocity, distribution coincide with the experimental data. Then the air drawing model of polymers in the melt blowing process established in Our previous research is solved with the aid Of simulation results of the air jet flow field. The final fiber diameter of the nonwoven fabrics predicted by the air drawing model of polymers tallies with the experimental data. The results show the great potential of this research for the computer assisted design of melt blowing technology and equipment. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1775-1779, 2009