The invention discloses a preparation method of a choline eutectic solvent and application of the choline eutectic solvent in extraction of flavonoid compounds. The preparation process of the cholineeutectic solvent is as follows: taking proper amounts of choline chloride or choline hydroxide for uniformly mixing with a proper amount of an organic acid according to a ratio (mole number) of 1:1-1:10; putting a uniformly mixed reactant into a flat-bottomed flask with a proper size, and then adding a proper amount of water to initiate a reaction; and putting a magnetic stirrer at the temperature of 25-50 DEG C, putting the flat-bottomed flask on a magnetic stirrer, performing stirring for 1-24h at a proper rotating speed, after reactants in the bottle become transparent and uniform viscousliquid, transferring the liquid in the bottle into a rotary evaporator, and performing spin-drying on excessive moisture to obtain a viscous transparent liquid, namely a DES solvent finished product.The flavonoid compound extracted by the method has the characteristics of high purity, high extraction rate and simple and convenient process, the extraction time is shortened, the traditional solventis changed into an environment-friendly DES solvent which is easy to decompose, and the flavonoid compound is a real green chemical.