A self-made single-roll stirring (SRS) machine was used to manufacture semisolid A2017 alloy, the mechanism of A2017 alloy formation was investigated. It was shown that A2017 dendrites growing on the rough roll surface are crashed into fragments by the roll, which move and grow freely then contribute the formation of finer spherical microstructure. When casting at 710-750 ℃, fine and homogeneous spherical or elliptical grains of A2017 alloy were obtained. Extending forming mould has been designed and was installed at the exit of roll-shoe gap. A2017 alloy was formed by extending continuously at the semisolid state on SRS machine. Through controlling pouring temperature, semisolid forming and extending extrusion was combined organically. A2017 product with fine surface and rectangular transection of 14 mm(25 mm was obtained. By contrast to the national standard, the fracture strength and elongation of A2017 products produced from extending semisolid extrusion have been improved with an increase of 100 MPa and 29%, respectively.