This　study　investigated　the　changes　in　microstructure　and　mechanical　properties　of　gas　tungsten　arc　welded　7075　aluminum　alloy　joints　using　ER5356　and　ER7150　filler　wire　subjected　to　post-weld　heat　treatment.　The　microstructure　and　mechanical　property　evolution　of　the　welds　was　analyzed　by　both　thermodynamics　calculations　and　experimental　methods.　After　welding,　alloying　elements　segregated　in　the　inter-dendritic　regions,　resulting　in　the　formation　of　excessive　intermetallic　compounds.　Within　the　welds　of　7075　aluminum　alloy　with　ER5356　filler　material,　the　inter-dendritic　region　was　primarily　composed　of　the　T-AlCuMgZn　phase.　In　contrast,　in　the　welds　of　7075　aluminum　alloy　with　ER7150　filler　material,　this　region　consisted　of　a　eutectic　mixture　containing　alpha-Al,　T-AlCuMgZn,　and　eta-MgZn2　phases.　The　alpha-Al　matrix　experienced　limited　supersaturation　due　to　the　presence　of　these　inter-dendritic　intermetallic　compounds,　which　could　not　dissolve　during　the　post-weld　aging　treatment.　As　a　comparison,　post-weld　solutioning　and　aging　treatment　significantly　improved　the　ultimate　tensile　strength　of　the　joints.　Among　all　the　samples,　the　7075　+　ER7150　sample　subjected　to　post-weld　solutioning　and　aging　treatment　exhibited　the　highest　strength　and　elongation,　primarily　attributed　to　the　complete　dissolution　of　the　inter-dendritic　intermetallic　compounds　and　the　formation　of　fine　precipitates.