The invention discloses a method for detecting phthalate in a water-based food simulant with a graphene/ionic liquid composite. The method includes the steps that the graphene/ionic liquid composite serves as an extraction agent, phthalate in water is extracted under ultrasonic assistance, elution is carried out with a back extraction agent, and phthalate in the water is analyzed in combination with the high performance liquid chromatography detection means. According to the method, repeated extraction is not needed, the sample use level is low, the solvent consumption is small, and the selectivity on phthalate is good; by adopting the high performance liquid chromatography detection means, operation is easy and convenient, and sensitivity is high.