Abstract: The air drawing model of polymer in melt blowing process is established by considering the effects of the variation of density and specific heat capacity at constant pressure of polymer melt with polymer temperature. The model is solved by introducing the numerical computation results of air jet flow field of the dual slot die, and model predictions of fiber diameter show good agreement with the experimental data. The effects of the processing parameters and die design parameters on fiber diameter are studied. It is found that lower polymer flow rate, higher initial polymer temperature, higher initial air velocity, smaller angle between the slot and the die axis, smaller width of the die head and larger width of the slot can all yield finer fibers.