Abstract: Sn_1-xBi_xO₂(x=0.0~0.2) nanoparticles about 40 nm were obtained using the DC arc plasma atomization method. The phase structures and morphologies of the powders were analyzed by XRD and TEM combined with high resolution image of powder selection area, and the grain sizes of the powders were calculated by half width method. The results show that the main crystalline phases of Bi-doped nanocomposite powders synthesized by DC arc plasma atomization method are tetragonal SnO₂, and that a small amount of Bi₂Sn₂O₇ with pyrochlore structure are found. The lattice constants of the particles were nearly to a=4.75 Å, c=3.19 Å, with orientation along the(110) and(101)planes for all proportions of the Bi-doped SnO₂. The morphology of the powder is spherical, with a small number of columnar crystals, and the small particles similar to the second phase in the grains are observed. When the powder with Bi₂O₃ content of 20%(mass friction) is treated at 1 320℃, agglomeration phenomenon is serious, and some Bi₂O₃ precipitated and segregated.