Abstract: The KFC copper alloy plates used for lead frame were cold rolled after solid solution, then cold rolling with different deformation were done between the two aging treatments at 500 ℃ and 400 ℃ respectively. The effect of the low temperature thermo-mechanical treatment on the microstructure and properties of the alloy was studies by means of optical microscopy, TEM, mechanical property test machine and conductivity analyzer. The results show that with increase of cold rolling deformation between the aging treatments from 0% to 90%, the dislocation increment of the alloy was more obviously and the precipitation of second phase was more sufficient. When the cold rolling deformation was 75%, the alloy had optimal comprehensive properties, the tensile strength was 417 MPa, the hardness was 126 HV, the elongation was 11%, the conductivity was 91.2 %IACS, and its thermal stability was good.