Novel ordered nickel chains with diameter 250-500 nm and length more than 5 mu m were synthesized under weak magnetic field by hydrazine reducing in ethylene glycol. The phase, morphology and magnetic properties were characterized by X-ray diffraction (XRD), scanning electron microanalyzer (SEM) and vibrating sample magnetometer (VSM), respectively. The results reveal that weak magnetic field leads to the fabrication of nickel chains paralleling each other with hierarchical structures. The growth mechanism and fabrication process of nickel magnetic nanocrystallites were discussed. (C) 2007 Elsevier B.V. All rights reserved.