Compound effects of B and Y additions on the microstructures and properties of a new type of high-strength and high-conductivity (HSHC) Cu–Mg–Te alloys are investigated on the aspects of purification and precipitation. Because of the purification function of B and Y additions, the tensile strength increased superlatively by the amplitude of 21.7% with a similar increase of elongation and the electrical conductivity of 4.2%. By comparison of the calculated decomposition pressures of B2O3 and Y2O3 at different temperatures, it can be concluded that the boron oxide is more stable than the yttrium oxide in the copper liquid, indicating the superior deoxygenization purification of the rare earth yttrium. The dispersive distribution of the Y–B compounds (YB6) was another factor for the improvement of the mechanical properties of the copper alloy. Finally, the copper alloy treated by hot rolling, cold rolling, and annealing processes in sequence exhibits HSHC with the tensile strength of 610.7 MPa and the electrical conductivity of 53.1%IACS.