To improve combustion properties of fuel oils, save energy and reduce pollution, the metal nanoparticles modified by fatty acids have been prepared. The dispersion capacities of these modified nanoparticles in liquid paraffin oil were examined, and were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectrum (FTIR) . The results show they possess similar crystal structure as organic shell, and average particle diameters, which are in agreement with their excellent oil-solubilities. Moreover, the properties of the modified nanoparticles additives in boiler fuel were evaluated by means of oxygen bomb relative method as regards energy saving and residual products lowering. The results show that the efficiency of combustion and decrement of residual products for fuels were improved to different degree. Therefore, notable economic and social benefits are brought.