Abstract: Effects of film cooling on the distribution of internal heat transfer coefficients of turbulent flow through a square channel were investigated experimentally and numerically.The main factors were the inlet Reynolds number and the hole distance ratio under turbulent condition.The investigation showed that the internal heat transfer coefficient was increased greatly with the increase of the inlet Reynolds number whereas its variation was not monotonous with the change of the hole distance ratio.The change of internal heat transfer characteristics was not obvious with hole distance variation.