In this paper, experiments have been conducted to study the heat transfer of a porous channel heat sink subjected to oscillating flow. The surface temperature distributions for both steady and oscillating flows were measured. The local and length-averaged Nusselt numbers were measured and analyzed. The experimental results revealed that the surface temperature distribution for oscillating flow is more uniform than that for steady flow. Due to the reversing flow direction, there are two thermal entrance regions for oscillating flow. The length-averaged Nusselt number for oscillating flow is much higher than that for steady flow. The porous channel heat sink subjected to oscillating flow can be considered as an effective method for cooling high-speed electronic devices.