NOVELTY - Preparation of 6-(N,N-dihydroxyethyl)-2,4-dichloro-1,3,5-triazine, involves: respectively adding the cyanuric chloride and diethanol amine containing the mole ratio of 1:1-1:3 into organic solvent and water containing volume ratio of 1:1-1:15, respectively preparing into cyanuric chloride organic solvent solution and diethanol amine water solution, continuously stirring, slowly dropping the diethanol amine water solution into cyanuric chloride organic solvent solution, until pH of the mixed solution is 6.5 plus minus 0.5, mixing liquid, vacuumizing to remove solvent. to obtain crude product.    USE - For preparation of 6-(N,N-dihydroxyethyl)-2,4-dichloro-1,3,5-triazine (claimed) useful for synthesizing anticancer medicine, inflaming retarding carbon forming protocol efficient agent and cross-linking agent and used as flame retardant, emulsifier and solvent.    ADVANTAGE - The 6-(N,N-dihydroxyethyl)-2,4-dichloro-1,3,5-triazine synthesized by the method overcomes the defects that the existing water phase yield is not high and the pollution is serious via the organic solvent method. The method requires little organic solvent dosage; is green and environment-friendly; and provides higher product yield compared with the water phase method.    DETAILED DESCRIPTION - Preparation of 6-(N,N-dihydroxyethyl)-2,4-dichloro-1,3,5-triazine, involves: respectively adding the cyanuric chloride and diethanol amine containing the mole ratio of 1:1-1:3 into organic solvent and water containing the volume ratio of 1:1-1:15, respectively preparing into cyanuric chloride organic solvent solution and diethanol amine water solution, continuously stirring at -4 to 5 degrees C, slowly dropping the diethanol amine water solution into cyanuric chloride organic solvent solution, until the pH of the mixed solution is 6.5 plus minus 0.5, stopping dropping diethanol amine water solution, fully reacting the mixing liquid for 1-5 hours, vacuumizing to remove the solvent to obtain 6-(N,N-dihydroxyethyl)-2,4-dichloro-1,3,5-triazine crude product, then washing by de-ionized water, filtering and drying under vacuum to obtain 6-(N,N-dihydroxyethyl)-2,4-dichloro-1,3,5-triazine purified product.