Abstract: An experimental study was made to obtain heat transfer data in a rectangular channel with two ribs and nine holes. The objectives were to investigate the effect of mass flow ratios and bleed holes area ratio on internal cooling. Test was performed with single bleed hole as well as with multiple holes. Steady-state heat transfer coefficients were obtained using thermochromic liquid crystal. The heat transfer enhancement was observed to largely depend on the placement of bleed hole on the inter-ribs surface. It was found that the area-averaged Nusselt number was enhanced more by placing the bleed hole behind the rib. The best enhancement occurred between 6% and 8%. The heat transfer of effective was improved obviously when the Renolds number was low relatively. Some conclusion can be obtained that the heat transfer was enhanced at the regions from the edge of holes to downstream section. The influence of area flow ratio was also tested. It was found that the best area flow ratio was about 2.5%~3.0%.