NaFe4P12 nanosprings were synthesized using a hydrothermal method at 170 degreesC for 24 h. The nanosprings are 1000-5000 nm in length and 200-1000 mn in diameter and consist of coiled nanobelts of 80-1-50 nm in width and 20-50 nm. in thickness. With an increase in the annealing time, the nanospring grows as a macrorod with a multilayered helical tubular structure. X-ray diffraction (XRD) patterns indicate that the nanosprings have the skutterudite crystal structure with cell parameter a = 7.782 Angstrom. Electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM) prove that the nanobelts grow along the (111) plane and that their growth direction is not parallel to the [ 110] direction in the growth plane. A possible growth process for NaFe4P12 nanosprings is suggested.