The invention provides a method for preparing cellulose nanowhiskers from corn husks. The method is characterized by comprising the following specific steps: performing pretreatment, biochemical treatment, mechanical crushing, DMSO (dimethyl sulfoxide) treatment and TEMPO (tetramethylpiperidinooxy) oxidation treatment, putting an obtained mixture into a stirrer, and stirring to obtain a corn husk fiber powder suspension; performing centrifugation treatment to obtain a corn husk fiber precipitate; performing dispersion treatment to obtain a corn husk cellulose nanowhisker suspension; and performing freeze-drying to obtain the corn husk cellulose nanowhiskers. The method provided by the invention has the advantages of simple preparation process, high yield, low energy consumption, no emission of toxic and harmful substances in the production process and large-scale popularization and application potential; and the used corn husks are rich in resources and low in cost, the problem of environmental pollution is solved, and the added value of the corn husks is also improved.