The invention relates to a dendrobium extract and application thereof in preparation of a skin-whitening and sun-screening agent. A preparation method of the dendrobium extract comprises the followingsteps: (1) drying and crushing dendrobium to obtain a material; (2) adding a right amount of ionic liquid solution into the material obtained in the step (1), soaking for 1-2h under the airtight condition, then adding an ethanol solution with volume fraction of 60-70%, heating up to reflux temperature, carrying out reflux extraction for 2-3h, filtering, collecting filtrate, and concentrating to obtain a crude extract; (3) diluting the crude extract, obtained in the step (2), with a right amount of water, adding hydrochloric acid to adjust the pH value to 2.0-5.0, then extracting for 2-3 timeswith ethyl ether, combining organic phases, carrying out vacuum concentration, and drying to obtain the dendrobium extract.