The effect of trace lithium on the anti corrosion ability of industrially pure copper has been studied. The experimental results show that trace lithium can improve the anti corrosion ability of pure copper in saturated NaCl solution, but the ability decreases with increasing lithium content. The improvement in the anti corrosion property results from the effect of lithium on purification, grain size, microstructure and lattice distortion of copper. The corrosion mechanism is oxidization and electric corrosion between copper and impurities.