The invention belongs to the technical field of biological environmental protection, and discloses a cable pit ash sluicing water treatment method. The method adopts a specific biological preparation to treat ash sluicing water, and the biological preparation is prepared through culturing Thiobacillus ferrooxidans, Thiobacillus thiooxidans, Pseudomonas aeruginosa, Sphingomonas sp. and Scenedesmus obliquus, and mixing with a specific carrier. The biological preparation prepared in the invention can effectively treat ash sluicing water wastewater.