Dioctyl phthalate (DOP) is characterized by a number of comprehensive properties, such as high plasticizing efficiency, low volatility and excellent UV-resisting [24]. Therefore, DOP was used in solvent-free procedure to design and synthesize two novel magnetic nano-sorbents. The first was based on surface encapsulation of nano-Fe3O4 by DOP for the formation of nano-Fe3O4-DOP sorbent. This magnetic nano-sorbent was further treated with triethylenetetramine (TETA) as an example of nitrogen donors containing sequestering reagent to produce nano-Fe3O4-DOP-TETA via also a solvent-free procedure. The produced magnetic nano-sorbents were characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), thermal gravimetric analysis (TGA), and Fourier transform-infrared spectroscopy (FT-IR). The metal sorption behaviors and characteristics of the newly designed magnetic nano-sorbents as magnetic solid phase extractors were investigated and explored by Ni(II), Cd(II) and Pb(II) under different experimental controlling factors and conditions.