Abstract: The effects of natural aging on mechanical properties and micro-structure of cold drawn dual-phase steel wire have been invastigated. It is found that the effect of natural aging for 6 monthe on the mechanical properties and microstructure of dual-phase steel wires is obvously, either of cold drawn or cold-drawn and followed by recovering before natural aging. In the case of cold-drawn, the tensile strength is increased during natural aging, while the ductility is reduced. However, in the case of cold-drawn and followed by recovering, the tensile strength is incresed during natural aging, while the ductility is also increased. The microstructures of steel wire have been observed by means of TEM. The resons of effect of natural aging on the mechanical properties were discussed.