The utility model discloses an aluminium alloy strip butt joint's welding auxiliary device, including supporting seat, first fastener and second fastener, wherein, the one end of first fastener and second fastener is all fixed on the supporting seat, and the other end is the free end, and the space of waiting to weld alloy strip is held to the constitution between the free end of first fastener and second fastener and the supporting seat, first fastener and second fastener be the installation side by side, and both will treat that two alloy strip of welded are fixed respectively, make two alloy strip's butt joint align. The utility model discloses simple structure, through first fastener and second fastener with alloy strip's butt joint alignment after -fixing on the supporting seat, the clearance of both convenient adjustment alloy strip butt joints guarantees that alloy strip's butt joint aligns, resoluble people's both hands or the foot of knocking off again, labour saving and time saving. The utility model discloses a have stronger fixed effect to alloy strip, prevent alloy strip's in welding process removal, guaranteed welding quality.