Abstract: A series of experiments were performed on the effects of different aging temperature and time in the range between 400~500 ℃ on the micro-morphology, physical properties, mechanical properties and strengthening mechanism of the Cu-2.1Ni-0.5Si-0.2Zr alloy, by using Microscope, SEM, eddy electrical conductivity tester, and universal materials testing machine. The results show the strength and electrical conductivity rapidly increased at early stages of aging. Then, the hardness decreased slowly after reaching peak value, while the conductivity continued to rise. The highest peak strength value of 665 MPa for the alloy aged at 450 ℃ for 2 h. There are two main types of precipitate spreads in the matrix of this alloy, Ni2Si phase and CuxZr phase. The formulas of Mott- Nabarro and Orowan can be used to explain the precipitation strengthening.