In order to overcome the safety problems caused by the mixed-packaging of small-bag-deoxidizer and foods, sodium oleate (NaOl) modified nano zero-valent iron (m-nZVI) was prepared by liquid phase reduction method with potassium borohydride (KBH4), which was fused with low density polyethylene (LDPE) and pressed into film by thermal press. The LDPE/m-nZVI composite film for packaging was prepared. The resultant materials were characterized and measured by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, universal testing machine and gas transmission rate tester. The results show that m-nZVI and LDPE were physical-blending. The presence of m-nZVI had no effects on thermal stability of LDPE. With increase in m-nZVI, the tensile strength and elongation at break of the composite films increased and then decreased. With m-nZVI weight fraction at 2%, the tensile strength and elongation at break of the composite films reached the maximum, increased by 41.4% and 23.4% respectively compared with the virgin LDPE film. The oxygen transmission coefficient of the composite film also decreased first and then increased. When the mass fraction of m-nZVI was 3%, the oxygen permeability coefficient of the composite film was the smallest, which was 40.9% lower than that of the virgin LDPE film. The addition of m-nZVI improved the composite film’s crystallization behaviors, and m-nZVI played the role of heterogeneous nucleation by improving the crystallization behavior of composite film, as well as the structure and properties of composite film, and enhanced the mechanical properties and barrier properties.