The invention provides a preparation method of carbon nanotube modified foamed ceramics. The preparation method comprises the following steps: adding inorganic ceramic particles and cationic surface active agent into deionized water, stirring at a high speed, enabling the cationic surface active agent to cover the surface of the inorganic ceramic particle, and then filtering and drying to obtain inorganic ceramic particles with positive charge; adding the inorganic ceramic particles and carbon nanotube into deionized water, enabling the inorganic ceramic particles with the positive charge to have electrostatic adsorption with carbon nanotube, and then filtering and drying to obtain composite powder; grinding the composite powder together with organic resin, performing hot pressing and sintering under the protection of nitrogen to obtain the carbon nanotube modified foamed ceramics. The carbon nanotube modified foamed ceramics are used as a reinforcing phase, so that on one hand, an effect of flexibilizing a foamed ceramic substrate can be achieved; on the other hand, the sound wave can be bounced for multiple times in a hollow structure of the carbon nanotube, so that a denoising effect can be realized. The preparation method is high in practicability.