In　this　paper,　4　mm-thick　AA7N01P-T4　was　welded　using　fiber　laser-variable　polarity　tungsten　inert　gas　(VPTIG)　hybrid　welding　with　filler　wire.　After　natural　aging　of　60　days,　microstructures　and　fatigue　properties　of　hybrid　welding　joints　were　investigated　by　Optical　Microscope　(OM),　Scanning　Electron　Microscope　(SEM)　equipped　with　Energy-Dispersive　Spectroscopy　(EDS),　Transmission　Electron　Microscope　(TEM),　Electron　Back　Scattered　Diffraction　(EBSD)　and　high-cycle　fatigue　&　fatigue　cracking　growth　rate　testing.　The　effect　of　reinforcement　on　the　fatigue　behavior　was　also　investigated.　The　experimental　results　shown　that　natural　aging　induced　the　amount　of　precipitates　enriched　with　Zn　and　Mg　and　the　dislocation　density　in　the　joint　to　increase,　and　the　precipitates　distributing　mainly　along　to　the　grain　boundaries.　Welding　reinforcement　has　significant　effect　on　the　fatigue　limit.　The　fatigue　limit　of　joint　with　reinforcement　is　115　MPa　and　the　fatigue　crack　is　initiated　along　to　the　weld　toe.　Whereas,　joints　without　reinforcement　show　the　fatigue　limit　of　160　MPa　and　the　fatigue　crack　initiation　and　final　fracture　both　in　weld　center.　For　the　same　aging　weld　without　reinforcement,　natural　aging　caused　the　fatigue　crack　growth　rate　to　slow　down　compared　to　as-welded　joint,　which　be　equivalent　to　that　of　heat-affected　zone　(HAZ)　and　BM.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.