By using SnCl2·2H2O as raw material ,the pure SnO2 thin films were prepared on the glass and quartz flat substrates by spray pyrolysis process. The crystal structure and surface morphology of the thin films were characterized by using XRD and SEM. The films which were prepared at 500 ℃ are smooth and fine. At 320 ℃, the films which were prepared for 50 min show relatively strong diffraction peak. At the same spray time, the strength of diffraction peak is enhanced when the temperature is 380 ℃.