Abstract: The aging precipitation of a Fe-Cu alloy cold-deformed 50% and 80% was studied. Optical microscope and HREM were employed to observe the microstructure and precipitation in thermo-mechanical processing, and the effect of cold deformation on the aging precipitation was analyzed. The results show that cold deformation is helpful to the precipitation of second phase, after a large quantity of cold deformation the precipitation is accelerated and the bulk volume of second phase becomes greater. Copper-rich transition phase is precipitated in advance and then transformed to ε-Cu phase with the increase of time during the overaging period. The copper-rich phase, i.e. GP zone, is the main cause to strengthen the alloy.