Cross-sectional microstructure of the SnO2 films on glass produced by the chemical vapor deposition (CVD) and spin coating process was investigated by high-voltage transmission electron microscopy (HVTEM). Thin cross-sections of the transparent SnO2 films on glass for TEM observation were prepared by the precision ion polishing system (PIPS) method to obtain large electron transparent area with high ion milling rates. HVTEM images and energy dispersive X-ray spectrometer (EDXS) analyses not only directly reveal the constitution of the transparent SnO2 films but also disclose the structural characteristics of the SnO2 conducting layer on an atomic scale. Moreover, it is found from the analysis of high-resolution electron microscope images by their digital diffractograms that the SnO2 conducting layer produced by spin coating process contains SnO microcrystal.