Abstract: Aniline methyl triethoxysilane (AMTS, 0.1 mL) was dissolved in 40 mL of N, N-dimethylformamide (DMF), and 0.5 g of prepared Fe₃O₄ NPs@SiO₂ was added, which reacted in an oil bath at 110 ℃ for 8 h. After cooling to room temperature, magnetic nanocomposite material Fe₃O₄NPs@SiO₂-AMTS was obtained, which was washed repeatedly with ethanol and water, and dried in vacuum at 80 ℃ for 10 h. 10 mL of water sample filtered through a 0.45 µm aqueous filter membrane was taken and adjusted to pH about 4.5 with hydrochloric acid, and 20 mg of magnetic nanocomposite material Fe₃O₄NPs@SiO₂-AMTS was added, which was extracted by ultrasound at room temperature for 20 min. The supernatant was discarded under the action of an external magnetic field. The residue was desorbed by ultrasound with 1 mL of acetonitrile for 10 min, the solution obtained was filtered through a 0.45 µm aqueous filter membrane, and high performance liquid chromatography-mass spectrometry was used to determine 6 phthalates ester (PAEs) in the filtrate, including di-n-octyl phthalate (DNOP), dimethyl phthalate (DMP), di(2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), and diethyl phthalate (DEP). As shown by the results, linear relationships between the ratios of the corresponding quantitative ion peak area to the internal standard quantitative ion peak area and mass concentrations of 6 PAEs were found in the range of 1.000-2 000 μg · L⁻¹, with detection limits (3S/N) in the range of 0.001 4-0.023 μg · L⁻¹. Test for recovery was made by the standard addition method, giving the results in the range of 66.0%-113%, which was better than those of HJ 1242—2022 (70.0%-130%). RSDs of the determined values for inter-day (n=6) and intra-day (n=18) were less than 15%.