SnO2 thin film on the glass fiber was prepared by the ethanol solvent and crystalline tin chloride based Sol-gel method, including the process of solution preparation, fiber dip-immersing, gel reaction and annealing. The sol was prepared by alcoholysis reaction of 0.9mol/l chloride- ethanol solvent under 80°C. A thin film of sol was prepared by dip-immersing process, then a post annealing process with various temperatures and time was adopted to form a stable crystallized film on the surface of the glass fiber. X-ray diffraction, scanning electron microscope (SEM) and fiber electric resistance measurement were utilized to characterize the transmittance and resistivity of the thin film With the rising of annealing temperature, the transmittance of the thin film was firstly increased and then decreased while the resistivity changed adversely. At last, an optimized annealing process with 550°C and 3h was chosen.