The Cu-Ti series alloys, strengthen by the spinodal decomposition during the heat treatment, are easy of losing strength and hardness after over aging, which need to add elements to optimize them. The effect of 0.1wt% zirconium addition on the spinodal decomposition and discontinuous precipitation of Cu-4Ti alloy has been studied. Microstructure was investigated by Optical Microscope (OM) and Transmission Electron Microscope (TEM). Mechanical properties and electrical conductivity (EC) were tested to show the properties of these alloys. The results show that spinodal decomposition process was retarded and discontinuous precipitation was suppressed by 0.1 wt% zirconium added to Cu-4Ti alloys, because of the hindering of zirconium to titanium’s diffusion. Zirconium elevated the properties of this alloy on peak aging at 450℃ for 7h. The zirconium has little influence on electrical conductivity of the Cu-4Ti-0.1Zr alloy. The tensile strength was 1155 MPa, microhardness was 330 and the electrical conductivity was 15.4%IACS.