The work aims to explore the effects of matching thickness as well as content and length of carbon fiber on absorbing properties of carbon fiber absorbing coating. The radar absorbing coating was prepared with chopped carbon fiber as absorbent and waterborne polyurethane as matrix resin. Morphology of the chopped carbon fiber and the coating was analyzed and characterized by using scanning electron microscope (SEM) and metallurgical microscope. Carbon fiber coating was matched with air layer, and absorbing properties of the coating were tested by using vector network analyzer. As thickness of the air matching layer increased from 1 mm to 3.5 mm, the maximum absorption peak moved from high frequency to low frequency. As the matching thickness was 3 mm, reflectivity peak was the lowest (?41 dB). As the thickness was 2.5 mm, the effective absorption frequency (