Abstract: A novel technique for the determination of trace organophosphorus pesticides(OPs) in vegetable by inductively coupled plasma-atomic emission spectrometry (ICP-AES) was established.The method was based on selective enrichment and separation of OPs from aqueous phase through magnetic nano-Fe3O4 (core)/ZrO2 (shell) (Fe3O4 @ ZrO2) by adding external magnetic field.The conditions for separation and enrichment of OPs were optimized.Methamidophos was selected as representative and the optium conditions such as adsorption time,amounts of adsorbent,elution concentration were considered.At pH=7.0,0.1 mg/L of methamidophos in 200 mL water samples was retained on 0.5 g Fe3O4 @ ZrO2 after shaking for 2 h.Extractions were performed by 10 mL 1.0 mol/L sodium hydroxide for 1 h.The recovery of 99.0% - 115% and detection limit of 4.4 μ g/L were obtained with relative standard deviations of 3.5% - 7.8%(n=4).The method could avoid the usage of organic extraction solvent because the protein,pigment,fiber in the vegetables did not interfere with the the adsorption of methamidophos.The OPs enrichment by Fe3O4 @ZrO2 could be up to 20 - 100 times,so its detection limit was lower than that of gas chromatography.The method was simple,accurate,sensitive and could be applied for enrichment,separation and determination of trace OPs residues in surface of vegetables.