Abstract: Carbon nanotubes are used as stealth absorbing materials. Research of detecting and evaluating absorbing performance of carbon nanotubes absorbing materials with different volume ratios becomes a hotspot in engineering. Based on the reflection model of electromagnetic waves in absorbing materials, a new method using reflection coefficients to characterize the absorbing performance of carbon nanotube absorbing materials was proposed. The equivalent resistance-capacitance network model was used to quantitatively analyze the dielectric properties of absorbing materials. A model of layered medium propagation was used to analyze the reflection characteristics of electromagnetic waves propagating in a metal-substrate absorbing medium. The simulation results of reflection that the carbon nanotube absorbing materials with different thickness and volume ratios show that when the thickness of carbon nanotube materials is greater than 1.4 mm, the materials begin to have absorbing properties. The center frequency of the absorption signal is shifted toward the low frequency. When the thickness is 2 mm and the volume ratio is 0.5%, the reflection coefficient is -19.07 dB, which is the smallest. When the thickness is 2.5 mm and the volume ratio is 1%, the -10 dB frequency band is the widest. The research lays a theoretical foundation for the fabrication and detection of carbon nanotube absorbing materials with different volume ratios, which has certain engineering application value in various fields.