Abstract: It is shown that mass flow velocity decreases gradually from the center to sides of mould wall during the extending extrusion process of semisolid A2107 alloy. In the middle of the way from the center to the side of the mould, there often is a transitional turbulence zone. These indicate that it is best to design a mould with smaller θ and without step a. Two sides of negative mould should be as equal as possible. When pouring temperature is higher than 790°C, due to thermal stress and alloy adhering on the mould, cracks would occur on the product surface. If pouring temperature is lower than 690°C, waves occur on the surface. The proper pouring temperature should be 710-750°C. A2017 product of 14 mm× 25 mm rectangular transection was achieved with fine surface. The fracture strength and elongation of the product are 100 MPa and 29% higher than normal requirements respectively.