The development trend for diagnostics is reducing the diameter of coaxial signal cables that comprise the probe cable. The thinner super-fine coaxial cable which is offering superior electronic and mechanical properties, such as 75 %IACS(International Annealed Copper Standard, electrical conductivity) and 700 ~ 800 MPa in tensile strength has to be developed. Cu-Ag based system is one of the most promising systems for high strength and high conductivity Cu alloys. In order to find the optimum conditions to obtain Cu-Ag-Zr-Co alloy with high strength and high electrical conductivity, the aging characteristics including work hardening of micro-Vickers hardness, tensile strength and electrical conductivity of this alloy were systematically measured at room temperature. Also the influence of aging treatment was investigated by transmission electron microscopy(TEM) and scanning electron microscopy(SEM) in this study. The aging treatment for precipitation was divided into two steps and carried out at various time and at different temperature and the multi-step aging treatment coupled with cold rolling was proposed for realizing Cu-Ag-Zr-Co alloys with high strength and high electrical conductivity. The electrical conductivity was improved from 31 %IACS to 91 %IACS remarkably and the tensile strength was increased from 230Mpa to 690Mpa greatly by an optimization of alloy composition and manufacturing process including aging.