The invention provides a method for separating a mixture of 2, 4-dichlorophenol and 2, 5-dichlorophenol. Based on the fundamental principle of supramolecular assembly, the method uses topology match between subjective molecules and objective molecules, and separates 2, 4 / 2, 5-mixed dichlorophenol by identifying molecules. Because of different molecular spatial structures of the 2, 4-dichlorophenol and the 2, 5-dichlorophenol and certain difference on polarities, specific different identifying capability among the subjective molecules exists, while difficulty or ease of intermolecular actions among the subjective molecules and other heterocyclic compound is different, therefore, the aim of separation can be achieved through identifying the molecules. The product obtained from the 2, 4 / 2, 5-mixed dichlorophenol by the method has high purity, and can be directly used after being separated, but does not need to be recrystallized to improve purity; and the method has high yield, is simple and practical, and is easy to industrialize.