Abstract: In view of the whole process of composite cooling on a turbine blade,this paper is composed of three parts.First the impingement-convection cooling on th internal surface of a blade leading edge is investigated,in result an empirical expression of internal-local heat transfer coefficients at the stagnation point is formulated and regularity of their variatons along the leading edge region is found.Secondly,the variations of the film-cooling effectiveness along the external surface of the leading edge are investigated according to various blowing ratios when the film jets ejected from the film holes on the blade.Thirdly,as the film jets impose some disturbances on the main stream,heat transfer is enhanced,as a result a set of empirical expressions for the external-local heat transfer coefficients are formulated.