A Fe3O4 nanoparticle and ultrasonic coupled dispersive liquid-liquid microextraction (NPsU-DLLME) method was developed for the preconcentration of lead from water, tobacco, and fertilizer samples. Imidazole-2,4-dicarboxylic acid was used as the chelating agent and carbon tetrachloride as the extractor solvent. Addition of certain amounts of Fe3O4 nanoparticles and specific exposure periods to ultrasonic waves were optimized. Maximum recovery (%) was obtained using the following conditions: 17.5 mL sample volume, sample pH 6, 100 mu L of carbon tetrachloride as the extraction solvent, 70 mu L of ethanol as the dispersing solvent, 100 mu L of 0.1% imidazole-2,4-dicarboxylic acid as the chelating agent, 100 mu L of a 0.1% Fe3O4 nanoparticle suspension, and a 1-minute exposure to ultrasonic waves. This method was validated using an SPS-WW2 Wastewater certified reference material. The limit of detection (LOD) was 5.3 mu g L-1, the limit of quantification (LOQ) 15.8 mu g L-1, and the relative standard deviation (RSD) 2.6%. The method was applied to the determination of lead in some water, tobacco, and fertilizer samples.