Recently, nitrogen alloyed steels have attracted the attention of researchers and industrial specialists due to their combination of strength and elongation. The identification of mechanical properties of nitrogen alloyed steels is very important for using these alloys with high reliability in various applications. Meanwhile, the resistance of material to crack propagation is one of the important parameters. Nowadays, nanoscience and computer simulations at nanoscale are noticed as the most studied subjects in the world. Molecular Dynamics Simulation (MDS) is one of the numerical methods at nanoscale which is the most deterministic method among available methods for the solution of molecular systems. The aim of this study is to simulate the crack propagation in Iron-Nitrogen nanocrystalline. In this regard, IronNitrogen nanocrystalline is modeled by applying Modified Embedded Atom Method (MEAM) interatomic potential using the related parameters for Iron-Nitrogen alloy. The microstructure of crack growth in nanocrystalline with dimension 100 40 3 A A A   are investigated under tensile loading with velocity magnitude of 0.8 Å /ps at temperature of 300K. The results show that crack velocity increases with the increase in crack length. The increase in the peak of radial distribution function curve during different time steps is as a result of change in the positions of particles during crack propagation. Also, the results indicates that the magnitudes of stress at three crystal directions has firstly nonlinear behavior and then changes to linear one which is due to the change of direction of crack growth during simulation time steps. Also, the track-growth direction and the track opening are investigated under simulation conditions.