The polymer air drawing model of polyamide melt blown nonwoven fabrics is established. The predicted fiber diameter coincides with the experimental data. The effects of the processing parameters on the fiber diameter are investigated. It is found that smaller polymer flow rate, higher initial polymer temperature, larger initial air velocity and larger die-to-collector distance can all produce finer fibers while too high initial air velocity and too large die-to-collector distance contribute little to the polymer drawing of polyamide melt. The results show great perspective of this research in the field of computer assisted design of the melt blowing technology.