Pure Bi2GeO5 nanorods were prepared in a liquid phase reaction followed by calcination of the precursor with a mixture of glycerol and ethanol as solvent and Bi(NO3)×5H2O and GeO2 as raw materials, and their phase and microstructure characterized. The prepared Bi2GeO5 nanorods were used in photocatalytic degradation of Rhodamine B (RhB). The result showed that the prepared Bi2GeO5 had a uniform rod shape and good stable photocatalytic activity. With the increase of concentration of Bi2GeO5 nanorods, their degradation effect firstly increased markedly, and then decreased. Their highest photodegradation rate reached 90.4% when their concentration was 1.5 g/L and the illumination time 150 min. Meanwhile, the formation mechanism of Bi2GeO5 nanorods was also analyzed as followed: in the hydrothermal process, first of all, the complexes with bismuth ions and ethylene glycol were self-assembly transformed into nanorod structure, and then the ion exchange reaction happened between the free germanium acid radical ions in the solution and the complexes with nanorod structure, and the Bi2GeO5 nanorods formed.