The invention belongs to the technical field of petrochemical engineering, and relates to the technical field of organic compound purification in the field of fine chemical engineering, in particularto a method for purifying 1,2,4-trichlorobenzene. The method for purifying 1,2,4-trichlorobenzene solves the technical problems that in the prior art, a high purity product of refined 1,2,4-trichlorobenzene is not obtained easily, and isomerization impurities are hard to control. The method has the advantages of being simple and efficient, easy to implement, good in atom economy, high in product purity and the like, isomerization in 1,2,4-trichlorobenzene is removed, and therefore the purity of 1,2,4-trichlorobenzene is improved. According to the technical scheme of the method for efficient hydrodechlorination purification of trichlorobenzene, the isomerization in 1,2,4-trichlorobenzene is converted into low-aryl chloride with the low boiling point, and 1,2,4-trichlorobenzene with the purity larger than 99.9% is obtained through distillation separation.