Combination of preparation and modification of carbon nanomaterials was realized through an attractive technological process based on two kinds of plasma methods in this study. An alternating current (AC) arc discharge plasma method in a fluidized bed had been employed for preparation of carbon nanomaterials with controlled structure, in which propane was cracked into carbon particles (CPs) and carbon nanotubes (CNTs). CPs were modified by using an atmospheric dielectric barrier discharge (DBD) air plasma in a downer. Parameters like type of metal electrodes, frequency of bipolar power supply and DBD plasma voltage were investigated. Size and morphology of CPs were characterized using scanning and transmission electron microscopy. A systematic study was carried out by diverse characterization methods on the analysis of microstructure and surface chemical composition. The results verified that kinds of metal electrodes played a dominant role in the formation of carbon nanomaterials in soot, the degree of graphitization of CPs increased with the increasing frequency in synthetic stage and plasma treatment voltage greatly enhanced oxygen and nitrogen content on CPs surface to change surface nature from hydrophobic to hydrophilic in modification step. (C) 2015 Elsevier B.V. All rights reserved.