Abstract: Detailed heat transfer measurements were performed by using 178 thermocouples in the channel with pin fin array.Local heat transfer coefficients and local heat transfer enhancement coefficients were obtained for the total eight Reynolds numbers ranging from 2000 to 100000 on the endwall of the channel.The endwall boundary conditions for the heat transfer investigation are heating bottom endwall and heating symmetrically on bottom and top endwalls.The mechanism of heat transfer enhancement with pin fin array has been elaborated.