"Experiments and molecular dynamics (MD) simulations have been conducted to investigate the nanoindentation behaviours of iron with body centered cubic (BCC) structure. The experiments show that the indentation hardness decreases with the indentation depth and it changes sharply for a small depth. Two cases with different crystallographic orientations have been simulated. The indentation plane is (010) for Case I and (111) for Case II, respectively. The calculated harness (17.4 GPa for Case I and 22.6 GPa for Case II) are in reasonable agreement with the experimental value (24.2 GPa). The simulation results show that the crystallographic orientation significantly influences the indentation deformation. Case I and Case II exhibit different deformation patterns. The indentation force and the hardness in Case I are smaller than Case II. It is also found that the pileup around the indenter is mainly formed along  direction for both cases."