Chlorothalonil, a kind of antiseptic used widely, has special control effect on plant disease caused by fungus of fruits. Its existing dose forms have many disadvantages including active ingredients exposing in wind, rain and sunshine, easy decomposition and volatilization. In order to solve above-mentioned problems, the best way is to microencapsulate chlorothalonil. In the study, chlorothalonil microcapsules were prepared by interfacial polymerization with toluene-2,4-diisocyanate and hexamethylenetetramine as wall materials. By large number of pre-experiments, the optimal shear speed, shear time, stirring speed, stirring time and suitable solvents used in preparation process of chlorothalonil microcapsules were determined. By orthogonal experiments, the optimal ratio of wall materials, solvent and dispersant were determined with encapsulation efficiency measured by ultraviolet spectrophotometry as indicator. The particle size distribution of chlorothalonil microcapsules prepared was even, and the encapsulation efficiency is up to 94.65%.