Abstract: Taking the butt welding process of 0.8 mm 6061 aluminum alloys micro-friction stir welding as the research object, using special tool and simulating the temperature field to pre-select the process parameters, their mechanical properties for different rotational speeds were compared by tensile test and the best welding parameter matching for the total were confirmed. The microstructures were studied by optical microscope and scanning electron microscopy. It is shown that the welded joints with superior mechanical properties can be got when the traversing speed reaches 300 mm/min and the rotational speed reaches 14 000 ~ 24 000 r/min, the tensile strength of which is above 70% of base metal. Compared with traditional friction stir welding, the HAZ of micro-structure of micro-friction stir welding seam only partially grew up, but some grains remained the same as the matrix without obvious change.