Cu-0.8Cr-0.12Zr-0.05Si ingots were prepared by vacuum melting and subjected to a two-stage aging treatment. The effects of different preaging times on the morphology of the Cr-rich precipitates and the mechanical properties of the alloy were studied. The microstructure evolution and properties of the samples under different preaging times were analysed. The results show that the sample with 50% rolling + 500 ℃ preaged for 15 min + 80% rolling + 450 ℃ aged for 2h has the best comprehensive performance. The hardness, yield strength, tensile strength and elongation are 201.7 HV, 582.7 MPa, 613.3 MPa and 14.2% , respectively, and the conductivity is 78.1% IACS . Compared with the traditional single-stage aging treatment of Cu-0.8Cr-0.12Zr-0.05Si alloy, the peak aging time is shortened by 2 h, and the conductivity is increased by 2.1%IACS. The precipitated phases of the sample preaged for 15 min are mainly spherical face-centered cubic Cr phase, whereas the precipitated phases of the sample preaged for 60 min are spherical and coffee bean-like body-centered cubic Cr phase. The calculation of the yield strength contribution reveals that precipitation strengthening is the main strengthening mechanism of the Cu-0.8Cr-0.12Zr-0.05Si alloy under two-stage aging.