The invention belongs to the field of water purifying, and discloses an industrial wastewater purifying agent, and a preparation method thereof. The preparation method comprises following steps: butyl titanate, carbon nano tube, brucite fiber, carboxylated nanocrystalline cellulose, absolute ethyl alcohol, and methylbenzene are mixed so as to obtain a solution A; absolute ethyl alcohol, glacial acetic acid, and water are mixed so as to obtain a solution B; the solution B is added into the solution A dropwise so as to obtain a sol solution; the sol solution is subjected to aging, absolute ethyl alcohol is added into the sol solution for solvent replacement, and normal hexane is added into the sol solution for solvent replacement; normal hexane is removed via separation so as to obtain a wet gel; the wet gel is subjected to hydrophobic modification; a composite aerogel is obtained via drying, and is prepared into particles or blocks so as to obtain the industrial wastewater purifying agent. The industrial wastewater purifying agent possesses high adsorption efficiency on oil stain and heavy metal, recycling of the industrial wastewater purifying agent is not necessary, and no secondary pollution on water body is caused.