Steel followed by aluminum alloys are the most frequently welded metal, while some metals cannot be effectively welded. In this work, two different aluminum alloys AA5052-O and AA6061-T6 are joined by MIG welding. Then compared the fatigue life of welded specimen at different loading conditions such as constant amplitude loading, constant amplitude loading with Intermediate single overload, variable amplitude loading. It has been found that welded AA6061-T6 alloy has more life than welded AA5052-O aluminum alloy. Fatigue life of welded alloy 6061-T6 and 5052-O is greater under block loading than intermediate single overloading.