Abstract: The nano-SnO₂ powder formed by sol-gel method is liable to agglomeration and recrystallization which is related to heating and temperature.By use of TEM the nanoparticles of SnO₂ were found to be micro-crystals less than 5nm.,which is formed after the pyrolysis of Sn（OH）4.These micro-crystals transformed to agglomeration during heating process and recrystallized when the temperature is above 400℃.When the temperature went up to 600℃ all the agglomeration transformed to crystal and the growth of dentrite formation were found.The experimental results will be effective to improve in sol-gel method.