Antimony-doped tin oxide thin films have a range of technical applications as conductive coatings, and sol–gel processing seems to offer some advantages over other coating techniques. In this study, undoped and antimony-doped tin oxide (ATO) thin films were prepared by sol–gel process in the solution of metal salts of tin (II) chloride dehydrate and antimony tri-chloride. It has been found that the heat-treatment temperature and doping level had strong influences on the microstructure and composition of Sb:SnO2 films. The microstructure of the thin films was analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The SnO2 crystals existed mainly as tetragonal rutile structure in the present work. The optimum heat-treatment temperature was about 450–500 ◦C, and the film was composed with nano-crystals and nano-pores. Compared with undoped tin oxide, doped antimony tin oxide films coated glass substrate were homogenenous in composition and morphology after being sintered at different temperatures. Electrical behavior of the doped films was discussed in terms of sheet resistance measured by four point probe. From the experimental data, the sheet resistance of the films could be as low as 100Ω/□.