Usually, early failures of anti-corrosion coating for marine engineering equipment are difficult to be detected in time, and indeed such failures are potential safety hazard. Herein, defects in coatings on steel plate were detected via electromagnetic induction infrared thermal imaging system, aiming in realizing non-destructive visual detection of coating defects. Meanwhile, qualitative evaluation criteria for different type of coating defects were proposed, according to the comprehensive assessment of the acquired infrared thermal images in terms of the color brightness difference throughout the image, the temperature difference between defects and their adjacent area, as well as the shape of defects in the acquired infrared thermal images. The established criteria of coating defect types may be used to identify defects occurred in coatings during their service process in marine environment, and the reliability of the criteria is verified by the Kelvin probe measured potential distribution and visible light images of the relevant coatings.