In order to give full play to the different performance advantages of dissimilar aluminum alloys and ehance the performace of aviation material， 6061-T6 aluminum alloy and 7075 aluminum alloy were selected for FSW test. Under the welding parameters of preheating time of 20 s， pressing volume of 0.1 mm， inclination of 2.5° and welding speed of 100 mm/min， the rotational speeds of 800，1 000， 1 200 and 1 500 r/min were tested respectively. Through the observation of the weld formation， mechanical properties and microstructure， the results show that when the rotating speed is 1 200 r/min， the surface of the weld is the best， and the tensile property is 255 MPa， which is 89.5% of 6061-T6 aluminum alloy. In the meanwhile， the heat generated by the forward side is higher than that generated by the backward side， so it is more suitable to place the metal with higher specific heat capacity and melting point in the forward side. Better appearance and performance of welded joint can be obtained through the test parameters in this paper.