A novel solution-phase method is developed for preparation of amorphous carbon nanoparticles with high specific surface area under ambient atmosphere by the reaction of ferrocene and ammonium chloride in polyethylene glycol 400 (PEG 400) at 200 oC. Samples are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption-desorption isotherms. It is found that the nanoparticles are complete amorphous and agglomerate together due to the strong surface tension. The amorphous carbon nanoparticles with a diameter of 40-100 nm have a wide size distribution of mesopores with a Brunauer-Emmett-Teller (BET) surface area of 402.28m2•g-1. It is proposed that the dissolved reactants uniformly dispersing in the solutions could react at a molecular level to form uniform carbon nanoparticles.