The FeOOH-gelatin complex nanoparticles are prepared by two-steps method. The obtained results by using SEM, TEM, FT-IR, XRD and VSM, show that the nanoparticles are obviously enwrapped by gelatin. At a constant molar ratio of FeCl₃/Fe₂(SO₄)₃/H₂O, the nanoparticles with 30～150 nm radius and weak magnetic property are prepared after sodium dodecylbenzenesulfonate (ABS) is added into FeCl₃/Fe₂(SO₄)₃/H₂O system. The maximal magnetic intensity is about 6.5×10^－6 emu/g. With the decrease of the molar ratio or the increase of gelatin content, the radius increases but the intensity decreases. The radius first enlarges and then reduces with solidification time.

Key words: FeOOH, nanoparticle, FeOOH-gelatin complex nanoparticle, magnetic property, preparation