In this work, germanium dioxide nanostructures were prepared by a facile co-precipitation method. In this synthesis approach was used from acetyl acetone as capping agent to get the smallest nanoparticles. Some of effective parameters were optimized to achieve the best morphology of product, such as mole ratio of acetyl acetone, temperature and time. Small germania nanostructures with a size about 70 nm sizes were achieved in this method. Nanostructures were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared techniques X-ray energy dispersive spectroscopy and ultraviolet spectroscopy (UV-Vis). Various properties such as photoluminescence, photocatalytic and photovoltaic property were studied for as-prepared nanostructures. Results of germania nanostructures show that product revealed a PL band that caused from recombination of electron and hole in nanostructure. On the other hand, these nanostructures show a good photocatalytic behavior for degradation of methyl orange in presence of UV light. Therefore germania nanoparticles applied in photovoltaic measurement.