Nickel powders with different morphologies, such as sphere, chain, and thorn-like nickel wire have been successfully synthesized by hydrazine reduction of NiCl2 in the presence of polyvinyl pyrrolidone (PVP) by using microwave-assisted chemical reduction method. The obtained products were characterized by XRD, SEM, TEM, and SAED techniques. Characterization by TEM and SAED showed that as-produced nickel powders were formed by self-assembly and aggregation of nanometer-sized nickel crystallites. PVP served as the structure directing agents and plays a key role for the morphology transformation of the nickel powders. In addition, compared with conventional heating method, microwave irradiation heating was in favor of the formation of nickel wires. The resultant nickel wires showed excellent electrical properties in the nickel wires/epoxy composite.