In this paper, Mn doped SnO nanomaterial is studied both experimentally and theoretically. Hexagonal-shaped Mn-doped SnO nanostructures are successfully synthesized by the simple template-free hydrothermal method. All theoretical results are calculated using ADF-BAND 2012.01. The experimental and the theoretical results prove the ferromagnetism of Mn doped SnO. The morphology, crystalline phase, particle sizes and atomic weight percentage of atoms are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDS), respectively. FESEM results show that the sheets-like SnO structure are in the range of 10 mu m and the average size of nano-hexagonal plates is about 100 nm. The average crystalline size of the tetragonal phase SnO particles is calculated to be about 25 nm from XRD results. Two Raman active modes A(1g) = 205 cm(-1) and B-1g = 106 cm(-1) and about 7 cm(-1) redshift are observed by the Raman spectroscopy. The experimental results are consistent with theoretical results.