The invention discloses a preparation method of a Clocythrin pesticide. The method comprises the following steps: a) mixing chrysanthemic acid and chrysanthemyl chloride and placing the mixture into a reaction vessel, adding triethylamine and introducing phosgene, slowly heating to 55-110 DEG C and fully reacting for 1-4 h so as to generate Chrysanthemoyl chloride; and b) dissolving sodium cyanide in an aqueous-phase Triton micellar solution, adding a catalyst and heating to 40 DEG C, slowly and dropwise adding mixed liquor of Chrysanthemoyl chloride and m-Phenoxybenzaldehyde, keeping the temperature and reacting for 1-4 h, cooling to 10 DEG C, adding a few amount of water and crystal seed, fully stirring and precipitating solids, and washing the precipitated solids with alkali, washing, filtering and drying so as to obtain a final product Clocythrin. The solvent in the invention can be recycled, use of the catalyst and water is reduced, and discharge of toxic wastewater and exhaust gas is minimized. The post-processing procedure is simple, and extraction and solvent distillation are not required. The final product can be obtained through simple centrifugation, washing and filtration. Discharge of solid wastes is decreased.