The invention discloses a preparation method and application of moringa oleifera leaf flavone with anticomplement and hypoglycemic activity. The preparation method includes: firstly adding moringa oleifera dried leaf powder into an ethanol solution to conduct ultrasonic extraction; using petroleum ether, ethyl acetate and n-butanol in order to conduct graded extraction on an extracted concentrated solution; carrying out pressure reduction concentration and vacuum freeze drying on the extracted solution to obtain powder A; dissolving the powder A in ethanol, passing the obtained product through a polyamide resin chromatographic column, using an ethanol solution to conduct gradient elution in order, and performing freeze drying to obtain powder B; dissolving the powder B in methanol, passing the obtained product through a Sephadex LH-20 chromatographic column, conducting methanol elution, collecting and combining the eluent, and carrying out concentration and freeze drying to obtain powder C; dissolving the powder C in methanol, using a preparative liquid phase reverse phase C18 column to conduct gradient elution, collecting the compound peaks eluted by 30%-35% methanol, and conducting concentrating and freeze-drying. The obtained flavone powder has purity up to more than 99%, and has strong anticomplement and alpha-glucosidase inhibitory activity.