Abstract: Polymer/metal composite structures were widely used in the engineering lightweight, however, it has large challenge for the direct connection of the two materials by welding. AA6061 Al alloy was firstly pretreated by laser method to create surface texture, then it was welded with polyimide by friction stir spot welding(FSSW). The effect of plunge depth on the microstructure and tensile-shear force of the FSSW joint was studied. The results show that the optimal plunge depth is 0.4 mm, and the tensile-shear load of the welded joint is 4553 N. The connection mechanism of polyimide/Al composite structure is mechanical interlocking at the interface between polyimide and AA6061.