Studying pollution of heavy metals in soil indispensable for maintaining the environment quality should be considered at different levels of decision making by researches. Cadmium is one ofthree big of heavy metals with the greatest potential hazard to humans and the environment. In this study,magnetic nanoparticles (FeCr 2 O 4 -MWCNTs) were prepared and modified by sol-gel method, The magnetic nanoparticles was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscope (AFM), and transmission electron microscopy (TEM). Preconcentration trace amount of cadmium(II) was analyzed in environmental samples by magnetic solid phase extraction. Detection in this technique was performed by flame atomic absorption spectroscopy. The best results were obtained in pH 7.0 of general buffered sample with rotating rate of 800 rpm, 1.5 mL eluent solution of nitric acid with 1.2 M concentration and in 25 minutes. The detection limit and RSD were 1.3 µg /L and 1.25 %respectively, with the enrichment factor 67. Finally, this technique was used for analyte measurement of soil of Isfahan steel company and zayandeh road river.