NOVELTY - Triclabendazole is prepared by adding 1,2,3-trichlorobenzene and potassium hydroxide, adding 4,5-dichloro-2-nitroaniline, xylene, and tetrabutylammonium bromide phase transfer catalyst, refluxing, cooling, drying, dissolving obtained 4-chloro-5-(2,3-dichlorophenoxy)-2-nitroaniline in ethanol solution, carrying out hydrogenation with presence of hydrogenation catalyst, adding potassium hydroxide and carbon disulfide, carrying out cyclization, dissolving obtained 5-chloro-6-(2,3-dichlorophenoxy)-2-mercapto-benzoimidazole, dimethyl sulfate, and potassium hydroxide in methanol, and reacting.    USE - Preparation of triclabendazole for veterinary medicine.    ADVANTAGE - The preparation has low cost and no pollution.    DETAILED DESCRIPTION - Triclabendazole is prepared by adding 1,2,3-trichlorobenzene and 50-65% potassium hydroxide in reaction container, refluxing for 6-7 hours, adding 4,5-dichloro-2-nitroaniline, xylene, and tetrabutylammonium bromide (TBAB) phase transfer catalyst, continuously refluxing at 120-180 degrees C for 7-8 hours, slowly stirring, cooling to room temperature, filtering out brown-yellow crystals, washing frozen crystals with xylene, washing with water until neutral, drying to obtain 4-chloro-5-(2,3-dichlorophenoxy)-2-nitroaniline, dissolving obtained compound in 75-80% ethanol solution, carrying out hydrogenation at 50-90 degrees C with presence of hydrogenation catalyst which is Raney nickel or palladium-carbon to obtain 4-chloro-5-(2,3-dichlorophenoxy)-p-phenylenediamine in which hydrogen donor is hydrazine hydrate, filtering catalyst, directly adding potassium hydroxide and carbon disulfide, carrying out cyclization at 60-80 degrees C to obtain 5-chloro-6-(2,3-dichlorophenoxy)-2-mercapto-benzoimidazole, dissolving obtained benzoimidazole compound, dimethyl sulfate, and potassium hydroxide in methanol, and reacting at 0-25 degrees C.    DESCRIPTION OF DRAWING(S) - The drawing shows a pattern of 4-chloro-5-(2,3-dichlorophenoxy)-2-nitroaniline.