A magnetic solid-phase extraction (MSPE) approach was developed based on well-designed Fe₃O₄-NH₂@g-C₃N₄ nanocomposite for simultaneous extraction of six benzophenones (BPs) in environmental water samples. The composite fabricated via in-situ self-assembled g-C₃N₄ shell with homogeneous polymerization of cyanuric chloride and cyanuric acid on Fe₃O₄-NH₂ core. While high adsorption capacity was derived from g-C₃N₄ via hydrophobic, π-π and hydrogen bonding interactions to the targets, the fast magnetic separation was realized with Fe₃O₄ core for less solvent consumption. In combination with LC-MS/MS, the Fe₃O₄-NH₂@g-C₃N₄ sorbent minimized the interfering components, reduced the matrix effects, and provided the enrichment factors of 121-150 for six BPs with relative standard deviations ≤ 9.7% even after 20 times extraction-desorption cycles. The present method gave the detection limits of 0.3-2.5 ng/L for six BPs with the linear ranges of 1.0-2000 ng/L, and the recoveries of 84.6%-104% in sea water and 86.2%-107% in lake water samples. Thus, the Fe₃O₄-NH₂@g-C₃N₄-based MSPE coupled with LC-MS/MS method provided a convenient, efficient, and reliable alternative to monitor trace BPs in environmental water samples.