In the de-icing technology of wind turbine blades, microwave de-icing, an environmentally friendly, efficient, and energy-saving method, has significant advantages over traditional de-icing techniques. Microwave de-icing utilizes microwave heating absorbing coatings, allowing the surface coatings of the blades to absorb microwave energy and convert it into heat energy. Therefore, studying the microwave absorption properties of coatings under microwave irradiation is crucial. In this paper, silicon carbide, iron (III) oxide, and graphite/polyurethane composite coatings with 12 different ratios and thicknesses were designed. Microwave heating experiments were conducted on the composite coatings using a 2.45 GHz frequency microwave to explore the effects of the coating ratio, coating thickness, microwave output power, and microwave irradiation distance on the microwave absorption properties of the composite coatings. The experimental results show that under the same conditions, the graphite/polyurethane composite absorbing coating heats the fastest, followed by the iron (III) oxide/polyurethane composite coating, and the silicon carbide/polyurethane composite coating heats the slowest. The microwave absorption properties of the composite coatings are positively correlated with the microwave output power and coating ratio, and negatively correlated with the microwave irradiation distance. However, they are also affected by the microwave heating conditions, where under the same microwave energy, the heating effect of the coating under low power for a long time is superior to that under high power for a short time.