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A comprehensive performance of formed parts is studied in Friction Stir Incremental Forming (FSIF). In this paper, various tool rotation speeds are set to form two typical parts (truncated funnel and pyramid frustum). Specifically, formability, surface quality, tensile strength, micro-hardness and thickness distribution are investigated and analyzed. Experimental results show that the formability generally increases as tool rotation speeds increase. On the contact surface, variation trends of the surface roughness are different in horizontal direction (parallel to tool path) and vertical direction (perpendicular to tool path). However, the surface roughness on the non-contact surface is almost not affected by tool rotation speed. Furthermore, mechanical properties including tensile strength and surface micro-hardness in formed parts are obviously enhanced compared to the initial sheet, of which the hardness values begin to fall down gradually after rotation speed reaches 3000 rpm. As for thickness measurement, more uniform thickness distribution of formed parts can be obtained at relative high tool rotation speeds. In general, parts formed at high rotation speed have a better comprehensive performance except the mechanical property.