In this paper, the authors studied the mineralogical, magnetic, phase and chemical composition characteristics of IIICD iron mereorite from Nandan, and compared this kind of mereorite with Argentine IAB iron meteorite and Siberian IIB Iron meteorite that belong to different chemical types, focusing on the weathering effects. The mineralogical characteristics of the sample were observed by means of polarizing microscope, hydrostatic weighing, and scanning electron microscope, and the magnetic properties, phases and chemical composition of iron meteorites were studied through vibrating sample magnetometer, X-ray diffraction and electron microprobe spectroscope semi-quantitative test. The results show that weathering can change the mineralogical properties of iron meteorite. With the strongly weathered iron meteorites from Nandan as an example, the authors have found that the luster is weakened to earthy luster, and the relative density is reduced. Moreover, antiferromagnetic substances produced by weathering can reduce the magnetism of iron meteorite. In addition, mineral phases also change greatly with secondary minerals of iron being such main phases as goethite (FeOOH) and magnetite (Fe₃O₄). Nevertheless, below its crust of weathering, the mineral phases and chemical composition have not changed significantly, and exist as kamacite and taenite phases dominated by Fe and Ni.