The recent rapid development of the nanotechnology has produced a considerable number of studies dedicated the usage of iron-based nanoparticles as soil and groundwater remediation materials. Magnetite nanoparticles (Fe3O4) have a strong reductive degradation ability, and the Fe2+ might play an important role as an electron donor to remain available for reaction with the chlorinated organic compounds [1]. Magnetite nanoparticles were prepared according to the method of chemical coprecipitation in the presence of poly-N-vinylpyrrolidone (PVP). Fe3O4/PVP nanoparticles aqueous colloidal solution at a concentration of 50 mg/kg of dry soil was used for treatment of long-term pesticides contaminated soil for 4 days. The major component of the pollution was trifluralin, the synthetic fluorinated dinitroaniline herbicide, it residue amounts 30 mg/kg dry soil. The biotest based on determination of the degree of wheat seeds growth demonstrated a stimulation effect, expressed in an increase in the length of the roots (by 178.5%) relative to the control without treatment. In aqueous system, trifluralin dissolved in acetone was mixed with Fe3O4/PVP nanoparticles powder (NP1) and Fe3O4/PVP nanoparticles aqueous colloidal solution (NP2), in concentration of 200 mg/l. After 14 days of treatment trifluralin remains 1.52% and 3.51% from the initial concentration of 0.15 mM, when used NP1 and NP2 correspondingly.