Abstract: Influence of working hardening effect on aging structures and properties of Cu-3.2Ni-0.75Si alloy is investigated through microstructure hardness method.It is indicated that the size and distribution of Ni 2Si phase after aging have obvious effect on working hardening and conductivity of the alloy.The structure aging at 450℃×8h shows the highest working hardening effect and its increase in microhardness is about Hv60 at cold rolling ratio of 80%.With the deformability increases,the fluctuation of microhardness aging at 550℃×8h is within a narrow range of about Hv10 at cold rolling ratio of 80%.The conductivity of the alloy decreases slowly with the increase of cold rolling ratio.At deformability of 80%,the alloy exhibits 6% IACS decrease of conductivity when aging at 450℃×4h,450℃×8h or 500℃×8h,but little variations when aging at 550℃×8h.