The mechanical properties, electrical conductivity and microstructures of 7055 aluminum alloy in various cold rolling reductions and tempers were investigated on the basis of tensile test, optical microscopy, X-ray diffraction and TEM. The results showed that the strength of 7055 alloy could be increased slightly after cold rolling and T6 aging at a smaller reduction, then decreased at a heavier rolling reduction, and always reduced with the increase of rolling reduction for the RRA temper alloy. The electrical conductivity of cold rolled 7055 alloy decreased with the increase of rolling reduction and increased for T6 and RRA temper alloys due to the lattice distortion and coarse precipitates from dislocations.