CaF2 nanostructures were synthesized from Ca-silicide powders by a diluted aqueous HF treatment. Commercially-available CaSi2 crystal powders and calcium silicide powders prepared by mechanical alloying were used as the source materials, and CaF2 nanosheet bundles and nanobunches of the CaF2 nanoparticles were obtained, respectively. The morphological property of the resulting CaF2 nanostructures was characterized by electron microscopy. It was found that the morphology of the resulting products depended on the starting materials. In addition, the growth mechanism of the CaF2 nanostructures was discussed from a topological synthesis point of view.