The invention discloses yeast nutritious food and a preparation method thereof. The yeast nutritious food adopts yeasts as a main raw material, comprises milk powder, maltodextrin , lactose, non-dairy creamer, calcium carbonate, starch, white granulated sugar, flavoring agent and essence and also comprises folic acid, B vitamins, vitamin A, vitamin C, selenium-rich yeast, zinc-rich yeast, chromium-rich yeast, iron-rich yeast, other trace elements-rich yeast, calcium carbonate, dehydrated onion slice, microcrystalline cellulose, starch, cocoa powder, fruit and vegetable powder, sesame, milk tea powder, soy-bean milk powder and oat flakes. The invention adopts multiple raw auxiliary materials, and can be used for preparing yeast nutritious food in such forms as powder, flakes and tablets through various preparation processes, so as to develop nutritious food with tastes applicable to various groups. Moreover, multiple raw auxiliary materials can be added. Compared with the existing yeast nutritious food, the yeast nutritious food of the invention has the function of significantly improving the immunity of the user.