Carbon nanofibers (CNFs) with large specific surface area have been conveniently prepared in accordance with the dipping, calcination and etching method without using any metal catalyst. The synthesized nanomaterials were characterized by means of low-angle X-ray diffraction, N-2 adsorption-desorption isotherm, scanning electron microscope and transmission electron microscope, etc., technique. And the adsorption activity of as-prepared CNFs was also investigated by adsorption of pollutant methylene blue in water. Results show that as-synthesized CNFs possess high aspect ratio, large specific surface area up to 973.4m(2)/g, pore volume of 0.875cm(3)/g and pore size of 1.7nm as well as a large amount of micropores. The specific surface area of as-prepared nanomaterials is far higher than that of carbon nanofibers prepared according to traditional method. And as-obtained CNFs display very high adsorption activities for the organic dyes in water, and the maximum adsorption capacity is up to 405.23mg/g. And that the adsorption process is well in conformity with pseudo-second-order kinetic model.