Abstract: The tube bundle of Air Cooler may encounter thickness thinning due to corrosion or erosion causes in the service, ultimately the tube explode or craze, leading to leakage of high-pressure and high-temperature medium. In order to avoid occurrence of burning and explosion accident, regular inspection of the tube bundle is required. In this paper the application of the Remote Field Eddy Thickness-testing technology in carbon steel tube bundles was discussed, the carbon steel tubes were inspected by Remote field eddy current thickness-testing in actual engineering and comparison test, and based on this, it was proposed that the remote field eddy thickness-testing method for finned carbon steel tube bundle is availability.