Nano-sized Antimony doped Tin Oxide(ATO) particles were synthesized by SnCl4 and SbCl5 as precursors using the DC Arc plasma. Doping level was enhanced by controlling Sb/Sn molar ratio. The ATO particles were characterized by XRD, TEM, SEM-EDX, TGA and BET. X-ray diffraction shows that all Sb ions were penetrated into the SnO2 lattice to substitute Sn ions. The average particle size of ATO particles was calculated from XRD data using Scherrer's equation and also from BET using the data of specific surface areas. TEM and SEM images show that the ATO nanoparticles were monodispersed in the range of 10-20nm.