Polyethylene glycol 4000 (PEG-4000), PEG-20000, and polyvinyl pyrrolidone (PVP) at various concentrations were used as dispersants for the preparation of iron nanoparticles with a liquid-phase reducing method. The effects of these non-ionic surfactants as dispersants were investigated to improve product dispersibility and reactivity. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), double-beam UV-visible spectrophotometry (UV), and atomic absorption spectrophotometry (AAS) were used to characterize and investigate the product and its effectiveness in removing lead (II). SEM analysis showed that all three surfactants improved the dispersibility of iron nanoparticles. Fine, fibrous iron nanoparticles were attained after adding PEG-4000 and PEG-20000, whereas fluffy particulate iron nanoparticles were obtained after adding PVP. The FT-IR results indicated that the three surfactants did not undergo chemical reactions during iron nanoparticle formation. Instead, they attached to or coated the surface of the nanoparticles through electrostatic interaction or van der Waals forces. The results of XRD demonstrated that the surfactants had no influence on the crystal phase of iron nanoparticles, and the UV results indicated the dispersion effects of PEG-20000 and PVP were superior to that of PEG-4000. The AAS results showed that the maximum adsorption capacity of lead (II) reached 229 mg/g when iron nanoparticles were prepared by adding 3% PEG-20000.