According to the aerothermodynamic analysis and turbulence characteristic analysis, there might be two main kinds of kinetic energy loss of the jets from rectangular nozzles for the blunt melt-blowing die. To reduce the energy loss, the new modified dies with stabilizing pieces are designed and compared with the blunt die. The air flow fields for the new dies are simulated using computational fluid dynamic technology, whereby the shear stress transport model is used for turbulence simulation. Three parameters (i.e., the velocity along the y-direction, the static temperature, and the turbulence intensity) are vitally important for producing fibers and thus are used to evaluate the performances of the slot dies. The simulation results reveal that the inner stabilizing pieces is helpful to decrease the negative velocity in the recirculation zone, enhance the downward centerline mean velocity, slow the centerline temperature decay, and make the air flow near the nose piece smoother. However, the external stabilizing pieces conduce only to increase the centerline velocity in the local area. POLYM. ENG. SCI., 54:110-116, 2014. (c) 2013 Society of Plastics Engineers