Abstract: In order to evaluate the effectiveness of an ice protection system in natural atmospheric icing conditions and reduce the flight test risks in icing conditions. Numerical analysis and validation for a wing hot-air anti-icing system in dry air conditions are investigated. The computational fluid dynamics (CFD) method was used for the simulation of the wing anti-icing system. The thermal boundary layer integral method was applied to acquire the external convective heat transfer coefficient. Surface equilibrium temperatures were obtained by coupling the external convective heat loss, the internal heat gain and the thermal conductivity through the skin. An improved method was proposed to exchange the values of the surface temperature and heat loads between the internal grid interface and the external grid interface. The method reduced the total cell number of the external flow field and accelerated the calculation speed.