The invention relates to the technical field of synthesis of a folic acid intermediate, in particular to a method for preparing 1,1,3-trichloroacetone through high-selectivity chlorination of acetone.The method comprises the process steps as follows: firstly, acetone is taken as a raw material and subjected to staged catalytic chlorination of chlorine, an amine compound is taken as a catalyst tochlorinate acetone to a dichloroacetone stage, then, an alcohol compound is added to serve as a solvent, water is added to adjust the reaction process, 1,1,3-trichloroacetone is prepared through deepchlorination, and the yield of the method is up to 90% or above. With the adoption of the technical scheme, the defects that existing preparation methods for 1,1,3-trichloroacetone have poorer synthesis technological level, low preparation efficiency and complex operation process and obtained products are low in selectivity can improved to a certain extent.