This study is to analyze the flow behavior of Newtonian and Carreau model fluids in a coextrusion wire coating die by finite element method. The effects of the change of the relative position of the coating materials and the operating conditions on the flow fields and investigated. A nonisothermal analysis is also carried out to take into ac-count the temperature rise due to viscous dissipation. The interface is positioned closer to the outer die wall when the lower viscous component forms the outer layer. The total pressure drop for the PS/LDPE system is nearly twice as large as that of the LDPE/PS system at the same wire velocity. The wall shear stress increases as the wire velocity increases and the PS/LDPE system has the larger value than the LDPE/PS system for both isothermal and nonisothermal condi-tions. The maximum temperature and the die exit temperature increase as the wire velocity increases. And the tem-perature rise due to viscous dissipation of molten polymer is higher when the higher viscous component forms the in-ner layer.