Abstract: The conjugate heat transfer of a 3-D wing hot-air anti-icing system was studied and a method for calculation of the surface temperature was presented in this paper.The method employed the commercial software package FLUENT and its user-defined functions(UDFs) to integrate tightly the external heat flux,internal heat flux and the thermal conduction in the skin.The external convective heat transfer coefficient was computed using the boundary layer integrated method,and the internal hot air flow and heat transfer was modeled using FLUENT.The iteration for the sequential coupling of internal,external and conductive heat transfer was implemented by automatically calculating the external heat flux and setting the heat flux boundary condition on the external surface with UDFs.This new method for a wing anti-icing system can be applied to verification of its feasibility and validity.