SnO 2 nanoparticles were prepared by citric acid assisted hydrothermal process and its microstructure and optoelectronic properties had been investigated. Based on XRD, TEM and FT-IR analyses, the SnO 2 crystallites with the tetragonal rutile structure were directly formed. The crystalline grain size of SnO 2 was 6.0nm and its specific surface area reached 206m 2 /g. The room temperature photoluminescence proved that it had a blue emission, which increased remarkably after SnO 2 calcined at 800°C.