Preparation method of insecticide acephate

The invention discloses a preparation method of an insecticide acephate. The preparation method of the insecticide acephate comprises the steps that phosgene and O,O,O-trimethyl sulfydryl phosphate react under the action of a catalyst for 1-4 hours, excessive phosgene is removed through nitrogen purging after the reaction, vacuum distillation is performed to remove methylclhlorofonmate, and the obtained liquid is O,S-dimethyl phosphoryl chloride; acetamide is dropwise added to the toluene solution of the O,S-dimethyl phosphoryl chloride, then an acid-binding agent is added, heating is performed to reach 20-60 DEG C, stirring reaction is performed for 2-6 hours, cooling is performed to reach room temperature, mixed liquid is obtained, and the acephate is obtained through post-treatment. The reaction process of the insecticide acephate prepared by adopting the preparation method is simple, the conditions are mild, the reagent and energy consumption is reduced, the post-treatment process is simple, extraction is not needed, the final product can be obtained through simple filtration and crystallization, the problem of environmental polluting waste liquid and waste gas emissions is basically not produced, and the requirements of environmental protection and energy saving are met.