Urea derivative aqueous two-phase system and application thereof

The invention discloses a urea derivative aqueous two-phase system and the application of the urea derivative aqueous two-phase system to separation and purification of a flavone-containing compound. The urea derivative aqueous two-phase system comprises a urea derivative shown in the formula I and an inorganic salt, wherein the inorganic salt is one or more of K2CO3, K2HPO4, KH2PO4 or ammonium sulfate, the mass fraction of the urea derivative in the aqueous two-phase system is 15%-25%, the mass fraction of the inorganic salt in the aqueous two-phase system is 10%-20%, the balance is water, and R1, R2, R3 and R4 in the formula I are respectively independent hydrogen, methyl or ethyl. The aqueous two-phase system has the effect of separating and purifying flavonoid substances, a target product is not denatured easily in the processes of separating and purifying, the distribution is balanced, the biological activity is kept, the time for extraction and phase separation is short, the extraction time is saved, en