In the present work, we report an extensive theoretical and experimental study in order to understood and determinate the structural and magnetic ground state of the MnFe3N. For such purpose, ab-initio calculations based on the Density Functional Density have been performed, considering the crystal structures Pm-3m (isostructural to γ′-Fe4N) and P4/mmm, and for each crystal structure different magnetic state have been regarded. Moreover, several experimental techniques such as X-ray diffraction, Mössbauer spectroscopy at room temperature and magnetization measurement at 5 K and 100 K were carried out. From the theoretical side, the P4/mmm crystal structure, where the magnetic moment of the atoms Mn and Fe has an antiparallel alignment, belong to ground state, and is supported by the experimental results.