The invention discloses a whitening cosmetic and a preparation method thereof. The present invention uses a variety of plant compositions as main raw materials, mainly including rice bran extract, rhodiola rosea extract, ginkgo leaf extract, tea polyphenols, lemon juice concentrate, chitosan, kudzu root extract, konjac fine powder , sunflower disc extract, sunflower seed kernel extract, saponins kernel, hemicellulose, honey; in addition, it also contains a small amount of glycerin, 1,3-propylene glycol, squalane, sodium hyaluronate, carbomer, three Ethanolamine, Allantoin, Nano Titanium Dioxide, Collagen Powder, Antibacterial, Isooctyl Ferulate and Glutathione. The composition can be used in whitening formulations, and has the effects of whitening skin, moisturizing, antibacterial and anti-inflammation, eliminating free radicals, inhibiting melanin formation, and inhibiting the activities of dopachrome intermutation enzyme and tyrosinase.