The invention provides a curcuma total sesquiterpene and tri-sesquiterpene monomer as well as a preparation method and application on an aspect of resisting diabetes. A curcuma plant is taken as a raw material and is subjected to supercritical CO2 extraction or organic solvent extraction, then, low-polarity organic solvent is used for extraction to obtain a low-polarity total sesquiterpene extractive, and the low-polarity total sesquiterpene extractive is subjected to further chromatographic separation to obtain three types of sesquiterpene pure products of curcumenol, curdione and zedoary epoxy ketone. Activity research indicates that the total sesquiterpene, the curcumenol, the curdione and the zedoary epoxy ketone can be used for effectively increasing the consumption of glucose of HepG2 cells so as to obtain antidiabetic activity, and the total sesquiterpene, the curcumenol, the curdione and the zedoary epoxy ketone can be used for preparing antidiabetic medicines, antidiabetic health care food, functional foods and the like. The invention researches and develops new application of the diabetes resistance of the sesquiterpene in curcuma plants, the medicine function range of the curcuma plant is expanded, a basis is provided for carrying out popularization, utilization and deep processing on traditional Chinese medicinal materials, and a new application direction is provided.