The invention relates to a method for preparation of a fluorescent aqueous two-phase system based on carbon quantum dots and a method for simultaneously realizing high efficient drug enrichment and high sensitivity detection through the fluorescent aqueous two-phase system. The method comprises uniformly mixing an ionic liquid and distilled water, adding the mixture into a round-bottom flask with phosphorus pentoxide, carrying out a heating reaction process to obtain hydrophilic carbon dots, then adding a certain amount of sodium dihydrogen phosphate and water into the hydrophilic carbon dots to obtain the fluorescent aqueous two-phase system, and finally determining a trace amount of drugs in a complex matrix through fluorescence quenching.