The　mechanism　of　fatigue　life　improvement　for　damaged　and　undamaged　copper　film　specimens　with　thickness　of　25um　was　investigated　by　laser　surface　irradiation　under　optimal　parameters　of　laser　irradiation　at　different　loading　levels.　The　results　showed　that　the　degree　of　improvement　in　fatigue　life　for　the　damaged　specimens　is　more　evident　when　the　applied　nominal　stress　was　larger.　The　hardening　induced　by　laser　irradiation　and　a　smooth　surface　feature　can　be　obtained　after　the　laser　irradiation　treatment,　which　results　in　fatigue　life　to　be　extended.　A　fatigue　life　prediction　method　was　proposed　by　the　view　of　equivalent　stress.　The　predicted　lives　by　the　proposed　prediction　method　were　in　good　agreement　with　the　experimental　results.