The invention relates to the technical field of medicine, in particular to application of benzoyl mesaconine, benzoyl aconine and benzoyl hypaconine in preparation of drugs or functional food for treating hypertension. According to animal experiments, the benzoyl mesaconine, the benzoyl aconine and the benzoyl hypaconine can significantly reduce the blood pressure of hypertensive rats, and the curative effect is good. The application has the advantages that (1) active components, including the benzoyl mesaconine, the benzoyl aconine and the benzoyl hypaconine, of monoester type alkaloids in monkshood have the characteristics of high efficiency and low toxicity in hypertension treatment, and the application prospect for development of the drugs and the functional food for treating the hypertension is very good; (2) the drugs and the functional food can be prepared on a large scale by artificial chemical synthesis techniques, and accordingly, a foundation is laid for low-cost and high-yield preparation in the development of the drugs and the functional food in the future.