In order to explore the optimal formulation of multi-spectral composite interfering agents and improve their interference performance in multiple wavelengths such as visible light, infrared and millimeter wave, carbon nanotube/ grapheme /carbon lightweight composites were prepared by the combination of material modification technology. The compound dispensing technology is used to prepare the multi-spectral composite interfering agents of “carbon nanotube/graphene/carbon composite material+carbon fiber”. Taking the sum of mass extinction coefficients of each band as the evaluation indicator，the different particle sizes of nanotubes/ grapheme /carbon composite materials （A）, different states of carbon fiber（B）, different mass ratios of carbon fiber（C）, and the different mixed solutions（D） as factors, the effects of various factors on the performance of the interfering agents were analyzed by the orthogonal experiment method. Based on the smoke box experiment, the mass extinction coefficient of the smoke screen was calculated according to the "Lambert-Beer" law. Results show that the extreme differences of factor A and factor C are 1.48 and 1.43, respectively, which are the main influencing factors on the overall shielding performance of composite interfering agents. The extreme differences of factor B and factor D are 0.32 and 0.52, respectively, which are the secondary influencing factors. The optimal preparation conditions are as follows: a carbon nanotube/graphene/carbon composite material having a particle diameter D₅₀ of 4.2 μm and a carbon fiber calcined at 800 ℃, which are mixed at a mass ratio of 85∶15 in an ethanol solution. The multi-spectral composite interfering agent prepared under those conditions has a transmittance of visible, near-infrared, mid-infrared and far-infrared light of less than 5% with an effective shielding time being more than 300 s, and an attenuation value of up to -14 dB and -15.65 dB on 3 mm and 8 mm wavebands with an effective masking time being greater than 30 s. The composite interfering agent prepared under those conditions has a better multi-spectral shielding performance.