Abstract: The long-term presence of non-steroidal anti-inflammatory drugs (NSAIDs) in the environmental water samples not only affects the life safety of aquatic organisms and disturbs the ecoenvironment, but also poses a serious threat to human health. In this study, amino-functionalized Fe₃O₄ nanoparticles (Fe₃O₄-NH₂) were firstly prepared by solvothermal method. Subsequently, polyethyleneimine (PEI) with a branched chain structure was successfully grafted onto Fe₃O₄ nanoparticles by Schiff base reaction in aqueous solution at room temperature using glutaraldehyde as a cross-linking agent, and a recyclable PEI-grafted magnetic nano-sorbent (Fe₃O₄@PEI) was synthesized and applied for the detection of NSAIDs in the environmental water samples. The compositional properties of Fe₃O₄@PEI were investigated by different characterization methods and the parameters affecting the extraction of NSAIDs were optimized. Due to high adsorption of Fe₃O₄@PEI for NSAIDs, the quantitative analysis of four NSAIDs in the environmental water samples, ketoprofen, naproxen, diclofenac and tolfenamic acid, was performed in combination with high-performance liquid chromatography. A good linear relationship between the chromatographic peak area and concentration was observed in the range of 1−500 µg/mL. The recoveries of the samples at three different spiked levels ranged from 85.6% to 107.8%; the intra-day precision was less than 7.8% (n=6); and the inter-day precision was less than 9.5% (n=3). The method is simple, rapid, accurate and reliable, and can be used for the analysis of NSAIDs in the environmental water samples．