The invention discloses yolk essence and a preparation method thereof. The preparation method comprises the following steps: taking yolk raw material, adding water and saccharose, uniformly mixing, sterilizing, introducing in aspergillus oryzae and aroma-producing yeast for fermentation, treating by a colloid mill to obtain yolk fermentation broth; adding mixed amino acids, thiamine, anhydrous milk fat and a solvent into the yolk fermentation broth, performing thermal reaction to obtain a yolk reactant; and adding yolk base, modified starch and xanthan gum in the yolk reactant, mixing uniformly, treating by the colloid mill to obtain paste yolk essence. According to the invention, natural yolk is used as the raw material, and the essence with the yolk flavor is prepared through microbial fermentation action and thermal reaction technology, the fragrance is rich and real, the cost is low, and the yolk essence has a great application market.