Abstract: The effects of heat exposure temperature on the microstructure and properties of 7050 aluminum alloy die forgings were investigated by the measurements of the tensile test, transmission electron microscope(TEM), and electrical conductivity. The results show that the strength of under-aged alloy increases and the elongation decreases after heat exposure.With the increase of heat exposure temperature, the strength of the alloy decreases and the electrical conductivity increases.When the thermal exposure temperature increases from 154℃ to 160℃, the tangential, radial and high tensile strength decrease to 564 MPa, 546 MPa and 549 MPa, with a decrease of 7.1%, 7.2% and 6.5%, respectively. Coarsening of η' phase and η phase should be responsible for the strength decrease of the 7050 aluminum alloy with the increase of heat epxosure temperature.