In the present study, a TiB2 particle-reinforced Cu/Cu-0.5Cr composite was prepared by vacuum arc melting (VAM). The microstructure, mechanical properties and electrical conductivity of the composite after heat treatment were studied. The results show that the micro–nano dual-scale particle-reinforced TiB2/Cu-0.5Cr (VAM) composite possessed high strength, high hardness and high electrical conductivity. The nano-Cr particles were uniformly dispersed in the copper matrix, and the particle size was below 20 nm. The TiB2 particles were also uniformly dispersed and had good bonding with the copper matrix. After peak aging at 475 °C for 4 h, the comprehensive properties of the TiB2/Cu-0.5Cr (VAM) composite were improved. The hardness and electrical conductivity were 99.6 HBW and 82.3% IACS, respectively. The tensile test results show that the tensile strength of the TiB2/Cu-0.5Cr (VAM) composite was 401 MPa, which is higher than that of the TiB2/Cu (VAM) composite. The TiB2/Cu-0.5Cr (VAM) composite had high strength and hardness due to the strengthening of the micro–nano dual-scale particles and the good interface bonding. Based on the tensile fracture morphology of the composite, the failure mechanism of the composite was determined and is discussed.